# Polynomial long division

Polynomial long division
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 This page uses content from Wikipedia. The original article was at Polynomial long division. The list of authors can be seen in the page history. As with Rosetta Code, the text of Wikipedia is available under the GNU FDL. (See links for details on variance)
In algebra, polynomial long division is an algorithm for dividing a polynomial by another polynomial of the same or lower degree.

Let us suppose a polynomial is represented by a vector, ${\displaystyle x}$ (i.e., an ordered collection of coefficients) so that the ${\displaystyle i}$th element keeps the coefficient of ${\displaystyle x^{i}}$, and the multiplication by a monomial is a shift of the vector's elements "towards right" (injecting ones from left) followed by a multiplication of each element by the coefficient of the monomial.

Then a pseudocode for the polynomial long division using the conventions described above could be:

degree(P):
return the index of the last non-zero element of P;
if all elements are 0, return -∞

polynomial_long_division(N, D) returns (q, r):
// N, D, q, r are vectors
if degree(D) < 0 then error
q0
while degree(N) ≥ degree(D)
dD shifted right by (degree(N) - degree(D))
q(degree(N) - degree(D)) ← N(degree(N)) / d(degree(d))
// by construction, degree(d) = degree(N) of course
dd * q(degree(N) - degree(D))
NN - d
endwhile
rN
return (q, r)

Note: vector * scalar multiplies each element of the vector by the scalar; vectorA - vectorB subtracts each element of the vectorB from the element of the vectorA with "the same index". The vectors in the pseudocode are zero-based.

• Error handling (for allocations or for wrong inputs) is not mandatory.
• Conventions can be different; in particular, note that if the first coefficient in the vector is the highest power of x for the polynomial represented by the vector, then the algorithm becomes simpler.

Example for clarification
This example is from Wikipedia, but changed to show how the given pseudocode works.

0    1    2    3
----------------------
N:  -42    0  -12    1        degree = 3
D:   -3    1    0    0        degree = 1

d(N) - d(D) = 2, so let's shift D towards right by 2:

N:  -42    0  -12    1
d:    0    0   -3    1

N(3)/d(3) = 1, so d is unchanged. Now remember that "shifting by 2"
is like multiplying by x2, and the final multiplication
(here by 1) is the coefficient of this monomial. Let's store this
into q:
0     1     2
---------------
q:   0     0     1

now compute N - d, and let it be the "new" N, and let's loop

N:  -42    0   -9    0        degree = 2
D:   -3    1    0    0        degree = 1

d(N) - d(D) = 1, right shift D by 1 and let it be d

N:  -42    0   -9    0
d:    0   -3    1    0        * -9/1 = -9

q:   0    -9     1

d:    0   27   -9    0

N ← N - d

N:  -42  -27    0    0        degree = 1
D:   -3    1    0    0        degree = 1

looping again... d(N)-d(D)=0, so no shift is needed; we
multiply D by -27 (= -27/1) storing the result in d, then

q:  -27   -9     1

and

N:  -42  -27    0    0        -
d:   81  -27    0    0        =
N: -123    0    0    0        (last N)

d(N) < d(D), so now r ← N, and the result is:

0   1  2
-------------
q:   -27  -9  1   →  x2 - 9x - 27
r:  -123   0  0   →          -123

## 11l

Translation of: Python
F degree(&poly)
L !poly.empty & poly.last == 0
poly.pop()
R poly.len - 1

F poly_div(&n, &D)
V dD = degree(&D)
V dN = degree(&n)
I dD < 0
exit(1)
[Float] q
I dN >= dD
q = [0.0] * dN
L dN >= dD
V d = [0.0] * (dN - dD) [+] D
V mult = n.last / Float(d.last)
q[dN - dD] = mult
d = d.map(coeff -> coeff * @mult)
n = zip(n, d).map((coeffN, coeffd) -> coeffN - coeffd)
dN = degree(&n)
E
q = [0.0]
R (q, n)

print(‘POLYNOMIAL LONG DIVISION’)
V n = [-42.0, 0.0, -12.0, 1.0]
V D = [-3.0, 1.0, 0.0, 0.0]
print(‘  #. / #. =’.format(n, D), end' ‘ ’)
V (q, r) = poly_div(&n, &D)
print(‘ #. remainder #.’.format(q, r))
Output:
POLYNOMIAL LONG DIVISION
[-42, 0, -12, 1] / [-3, 1, 0, 0] =  [-27, -9, 1] remainder [-123]

procedure Long_Division is
package Int_IO is new Ada.Text_IO.Integer_IO (Integer);
use Int_IO;

type Degrees is range -1 .. Integer'Last;
subtype Valid_Degrees is Degrees range 0 .. Degrees'Last;
type Polynom is array (Valid_Degrees range <>) of Integer;

function Degree (P : Polynom) return Degrees is
begin
for I in reverse P'Range loop
if P (I) /= 0 then
return I;
end if;
end loop;
return -1;
end Degree;

function Shift_Right (P : Polynom; D : Valid_Degrees) return Polynom is
Result : Polynom (0 .. P'Last + D) := (others => 0);
begin
Result (Result'Last - P'Length + 1 .. Result'Last) := P;
return Result;
end Shift_Right;

function "*" (Left : Polynom; Right : Integer) return Polynom is
Result : Polynom (Left'Range);
begin
for I in Result'Range loop
Result (I) := Left (I) * Right;
end loop;
return Result;
end "*";

function "-" (Left, Right : Polynom) return Polynom is
Result : Polynom (Left'Range);
begin
for I in Result'Range loop
if I in Right'Range then
Result (I) := Left (I) - Right (I);
else
Result (I) := Left (I);
end if;
end loop;
return Result;
end "-";

procedure Poly_Long_Division (Num, Denom : Polynom; Q, R : out Polynom) is
N : Polynom := Num;
D : Polynom := Denom;
begin
if Degree (D) < 0 then
raise Constraint_Error;
end if;
Q := (others => 0);
while Degree (N) >= Degree (D) loop
declare
T : Polynom := Shift_Right (D, Degree (N) - Degree (D));
begin
Q (Degree (N) - Degree (D)) := N (Degree (N)) / T (Degree (T));
T := T * Q (Degree (N) - Degree (D));
N := N - T;
end;
end loop;
R := N;
end Poly_Long_Division;

procedure Output (P : Polynom) is
First : Boolean := True;
begin
for I in reverse P'Range loop
if P (I) /= 0 then
if First then
First := False;
else
Put (" + ");
end if;
if I > 0 then
if P (I) /= 1 then
Put (P (I), 0);
Put ("*");
end if;
Put ("x");
if I > 1 then
Put ("^");
Put (Integer (I), 0);
end if;
elsif P (I) /= 0 then
Put (P (I), 0);
end if;
end if;
end loop;
New_Line;
end Output;

Test_N : constant Polynom := (0 => -42, 1 => 0, 2 => -12, 3 => 1);
Test_D : constant Polynom := (0 => -3, 1 => 1);
Test_Q : Polynom (Test_N'Range);
Test_R : Polynom (Test_N'Range);
begin
Poly_Long_Division (Test_N, Test_D, Test_Q, Test_R);
Put_Line ("Dividing Polynoms:");
Put ("N: "); Output (Test_N);
Put ("D: "); Output (Test_D);
Put_Line ("-------------------------");
Put ("Q: "); Output (Test_Q);
Put ("R: "); Output (Test_R);
end Long_Division;

output:

Dividing Polynoms:
N: x^3 + -12*x^2 + -42
D: x + -3
-------------------------
Q: x^2 + -9*x + -27
R: -123

## ALGOL 68

BEGIN # polynomial division                                         #
# in this polynomials are represented by []INT items where    #
# the coefficients are in order of increasing powers, i.e.,   #
# element 0 = coefficient of x^0, element 1 = coefficient of  #
# x^1, etc.                                                   #

# returns the degree of the polynomial p, the highest index of  #
#         p where the element is non-zero or - max int if all   #
#         elements of p are 0                                   #
OP   DEGREE = ( []INT p )INT:
BEGIN
INT result := - max int;
FOR i FROM LWB p TO UPB p DO
IF p[ i ] /= 0 THEN result := i FI
OD;
result
END # DEGREE # ;

MODE POLYNOMIALDIVISIONRESULT = STRUCT( FLEX[ 1 : 0 ]INT q, r );

# in-place multiplication of the elements of a by b returns a   #
OP   *:= = ( REF[]INT a, INT b )REF[]INT:
BEGIN
FOR i FROM LWB a TO UPB a DO
a[ i ] *:= b
OD;
a
END # *:= # ;
# subtracts the corresponding elements of b from those of a,    #
#           a and b must have the same bounds - returns a       #
OP   -:= = ( REF[]INT a, []INT b )REF[]INT:
BEGIN
FOR i FROM LWB a TO UPB a DO
a[ i ] -:= b[ i ]
OD;
a
END # -:= # ;
# returns the polynomial a right-shifted by shift, the bounds    #
#         are unchanged, so high order elements are lost         #
OP   SHR = ( []INT a, INT shift )[]INT:
BEGIN
INT da = DEGREE a;
[ LWB a : UPB a ]INT result;
FOR i FROM LWB result TO shift - ( LWB result + 1 ) DO result[ i ] := 0 OD;
FOR i FROM shift - LWB result TO UPB result DO result[ i ] := a[ i - shift ] OD;
result
END # SHR # ;

# polynomial long disivion of n in by d in, returns q and r      #
OP   / = ( []INT n in, d in )POLYNOMIALDIVISIONRESULT:
IF DEGREE d < 0 THEN
print( ( "polynomial division by polynomial with negative degree", newline ) );
stop
ELSE
[ LWB d in : UPB d in ]INT d := d in;
[ LWB n in : UPB n in ]INT n := n in;
[ LWB n in : UPB n in ]INT q; FOR i FROM LWB q TO UPB q DO q[ i ] := 0 OD;
INT dd in = DEGREE d in;
WHILE DEGREE n >= dd in DO
d := d in SHR ( DEGREE n - dd in );
q[ DEGREE n - dd in ] := n[ DEGREE n ] OVER d[ DEGREE d ];
# DEGREE d is now DEGREE n                          #
d *:= q[ DEGREE n - dd in ];
n -:= d
OD;
( q, n )
FI # / # ;

# displays the polynomial p                                      #
OP   SHOWPOLYNOMIAL = ( []INT p )VOID:
BEGIN
BOOL first := TRUE;
FOR i FROM UPB p BY - 1 TO LWB p DO
IF INT e = p[ i ];
e /= 0
THEN
print( ( IF   e < 0 AND first THEN "-"
ELIF e < 0           THEN " - "
ELIF           first THEN ""
ELSE                      " + "
FI
, IF ABS e = 1 THEN "" ELSE whole( ABS e, 0 ) FI
)
);
IF i > 0 THEN
print( ( "x" ) );
IF i > 1 THEN print( ( "^", whole( i, 0 ) ) ) FI
FI;
first := FALSE
FI
OD;
IF first THEN
# degree is negative                                 #
print( ( "(negative degree)" ) )
FI
END # SHOWPOLYNOMIAL # ;

[]INT n = ( []INT( -42, 0, -12, 1 ) )[ AT 0 ];
[]INT d = ( []INT(  -3, 1,   0, 0 ) )[ AT 0 ];

POLYNOMIALDIVISIONRESULT qr = n / d;

SHOWPOLYNOMIAL n; print( ( " divided by " ) ); SHOWPOLYNOMIAL d;
print( ( newline, " -> Q: " ) ); SHOWPOLYNOMIAL q OF qr;
print( ( newline, "    R: " ) ); SHOWPOLYNOMIAL r OF qr

END
Output:
x^3 - 12x^2 - 42 divided by x - 3
-> Q: x^2 - 9x - 27
R: -123

## APL

div{
{
q r d
(d) > nr : q r
c  (⊃⌽r) ÷ ⊃⌽d
(c,q) ((¯1r) - c × ¯1(-n)d) d
}
}
Output:
N←¯42 0 ¯12 1
D←¯3 1
⍪N div D
¯27 ¯9 1
¯123

## BBC BASIC

DIM N%(3) : N%() = -42, 0, -12, 1
DIM D%(3) : D%() =  -3, 1,   0, 0
DIM q%(3), r%(3)
PROC_poly_long_div(N%(), D%(), q%(), r%())
PRINT "Quotient = "; FNcoeff(q%(2)) "x^2" FNcoeff(q%(1)) "x" FNcoeff(q%(0))
PRINT "Remainder = " ; r%(0)
END

DEF PROC_poly_long_div(N%(), D%(), q%(), r%())
LOCAL d%(), i%, s%
DIM d%(DIM(N%(),1))
s% = FNdegree(N%()) - FNdegree(D%())
IF s% >= 0 THEN
q%() = 0
WHILE s% >= 0
FOR i% = 0 TO DIM(d%(),1) - s%
d%(i%+s%) = D%(i%)
NEXT
q%(s%) = N%(FNdegree(N%())) DIV d%(FNdegree(d%()))
d%() = d%() * q%(s%)
N%() -= d%()
s% = FNdegree(N%()) - FNdegree(D%())
ENDWHILE
r%() = N%()
ELSE
q%() = 0
r%() = N%()
ENDIF
ENDPROC

DEF FNdegree(a%())
LOCAL i%
i% = DIM(a%(),1)
WHILE a%(i%)=0
i% -= 1
IF i%<0 EXIT WHILE
ENDWHILE
= i%

DEF FNcoeff(n%)
IF n%=0 THEN = ""
IF n%<0 THEN = " - " + STR$(-n%) IF n%=1 THEN = " + " = " + " + STR$(n%)

Output:

Quotient =  + x^2 - 9x - 27
Remainder = -123

## C

Translation of: Fortran
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <assert.h>
#include <gsl/gsl_vector.h>

#define MAX(A,B) (((A)>(B))?(A):(B))

void reoshift(gsl_vector *v, int h)
{
if ( h > 0 ) {
gsl_vector *temp = gsl_vector_alloc(v->size);
gsl_vector_view p = gsl_vector_subvector(v, 0, v->size - h);
gsl_vector_view p1 = gsl_vector_subvector(temp, h, v->size - h);
gsl_vector_memcpy(&p1.vector, &p.vector);
p = gsl_vector_subvector(temp, 0, h);
gsl_vector_set_zero(&p.vector);
gsl_vector_memcpy(v, temp);
gsl_vector_free(temp);
}
}

gsl_vector *poly_long_div(gsl_vector *n, gsl_vector *d, gsl_vector **r)
{
gsl_vector *nt = NULL, *dt = NULL, *rt = NULL, *d2 = NULL, *q = NULL;
int gn, gt, gd;

if ( (n->size >= d->size) && (d->size > 0) && (n->size > 0) ) {
nt = gsl_vector_alloc(n->size); assert(nt != NULL);
dt = gsl_vector_alloc(n->size); assert(dt != NULL);
rt = gsl_vector_alloc(n->size); assert(rt != NULL);
d2 = gsl_vector_alloc(n->size); assert(d2 != NULL);
gsl_vector_memcpy(nt, n);
gsl_vector_set_zero(dt); gsl_vector_set_zero(rt);
gsl_vector_view p = gsl_vector_subvector(dt, 0, d->size);
gsl_vector_memcpy(&p.vector, d);
gsl_vector_memcpy(d2, dt);
gn = n->size - 1;
gd = d->size - 1;
gt = 0;

while( gsl_vector_get(d, gd) == 0 ) gd--;

while ( gn >= gd ) {
reoshift(dt, gn-gd);
double v = gsl_vector_get(nt, gn)/gsl_vector_get(dt, gn);
gsl_vector_set(rt, gn-gd, v);
gsl_vector_scale(dt, v);
gsl_vector_sub(nt, dt);
gt = MAX(gt, gn-gd);
while( (gn>=0) && (gsl_vector_get(nt, gn) == 0.0) ) gn--;
gsl_vector_memcpy(dt, d2);
}

q = gsl_vector_alloc(gt+1); assert(q != NULL);
p = gsl_vector_subvector(rt, 0, gt+1);
gsl_vector_memcpy(q, &p.vector);
if ( r != NULL ) {
if ( (gn+1) > 0 ) {
*r = gsl_vector_alloc(gn+1); assert( *r != NULL );
p = gsl_vector_subvector(nt, 0, gn+1);
gsl_vector_memcpy(*r, &p.vector);
} else {
*r = gsl_vector_alloc(1); assert( *r != NULL );
gsl_vector_set_zero(*r);
}
}
gsl_vector_free(nt); gsl_vector_free(dt);
gsl_vector_free(rt); gsl_vector_free(d2);
return q;
} else {
q = gsl_vector_alloc(1); assert( q != NULL );
gsl_vector_set_zero(q);
if ( r != NULL ) {
*r = gsl_vector_alloc(n->size); assert( *r != NULL );
gsl_vector_memcpy(*r, n);
}
return q;
}
}

void poly_print(gsl_vector *p)
{
int i;
for(i=p->size-1; i >= 0; i--) {
if ( i > 0 )
printf("%lfx^%d + ",
gsl_vector_get(p, i), i);
else
printf("%lf\n", gsl_vector_get(p, i));
}
}

gsl_vector *create_poly(int d, ...)
{
va_list al;
int i;
gsl_vector *r = NULL;

va_start(al, d);
r = gsl_vector_alloc(d); assert( r != NULL );

for(i=0; i < d; i++)
gsl_vector_set(r, i, va_arg(al, double));

return r;
}
int main()
{
int i;
gsl_vector *q, *r;
gsl_vector *nv, *dv;

//nv = create_poly(4,  -42., 0., -12., 1.);
//dv = create_poly(2,  -3., 1.);
//nv = create_poly(3,  2., 3., 1.);
//dv = create_poly(2,  1., 1.);
nv = create_poly(4, -42., 0., -12., 1.);
dv = create_poly(3, -3., 1., 1.);

q = poly_long_div(nv, dv, &r);

poly_print(q);
poly_print(r);

gsl_vector_free(q);
gsl_vector_free(r);

return 0;
}

### Another version

Without outside libs, for clarity. Note that polys are stored and show with zero-degree term first:

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>

typedef struct {
int power;
double * coef;
} poly_t, *poly;

#define E(x, i) (x)->coef[i]

/* passing in negative power to have a zeroed poly */
poly p_new(int power, ...)
{
int i, zeroed = 0;
va_list ap;

if (power < 0) {
power = -power;
zeroed = 1;
}

poly p = malloc(sizeof(poly_t));
p->power = power;
p->coef = malloc(sizeof(double) * ++power);

if (zeroed)
for (i = 0; i < power; i++) p->coef[i] = 0;
else {
va_start(ap, power);
for (i = 0; i < power; i++)
E(p, i) = va_arg(ap, double);
va_end(ap);
}

return p;
}

void p_del(poly p)
{
free(p->coef);
free(p);
}

void p_print(poly p)
{
int i;
for (i = 0; i <= p->power; i++)
printf("%g ", E(p, i));
printf("\n");
}

poly p_copy(poly p)
{
poly q = p_new(-p->power);
memcpy(q->coef, p->coef, sizeof(double) * (1 + p->power));
return q;
}

/* p: poly;  d: divisor;  r: remainder; returns quotient */
poly p_div(poly p, poly d, poly* r)
{
poly q;
int i, j;
int power = p->power - d->power;
double ratio;

if (power < 0) return 0;

q = p_new(-power);
*r= p_copy(p);

for (i = p->power; i >= d->power; i--) {
E(q, i - d->power) = ratio = E(*r, i) / E(d, d->power);
E(*r ,i) = 0;

for (j = 0; j < d->power; j++)
E(*r, i - d->power + j) -= E(d, j) * ratio;
}
while (! E(*r, --(*r)->power));

return q;
}

int main()
{
poly p = p_new(3, 1., 2., 3., 4.);
poly d = p_new(2, 1., 2., 1.);
poly r;
poly q = p_div(p, d, &r);

printf("poly: "); p_print(p);
printf("div:  "); p_print(d);
printf("quot: "); p_print(q);
printf("rem:  "); p_print(r);

p_del(p);
p_del(q);
p_del(r);
p_del(d);

return 0;
}

## C#

Translation of: Java
using System;

namespace PolynomialLongDivision {
class Solution {
public Solution(double[] q, double[] r) {
Quotient = q;
Remainder = r;
}

public double[] Quotient { get; }
public double[] Remainder { get; }
}

class Program {
static int PolyDegree(double[] p) {
for (int i = p.Length - 1; i >= 0; --i) {
if (p[i] != 0.0) return i;
}
return int.MinValue;
}

static double[] PolyShiftRight(double[] p, int places) {
if (places <= 0) return p;
int pd = PolyDegree(p);
if (pd + places >= p.Length) {
throw new ArgumentOutOfRangeException("The number of places to be shifted is too large");
}
double[] d = new double[p.Length];
p.CopyTo(d, 0);
for (int i = pd; i >= 0; --i) {
d[i + places] = d[i];
d[i] = 0.0;
}
return d;
}

static void PolyMultiply(double[] p, double m) {
for (int i = 0; i < p.Length; ++i) {
p[i] *= m;
}
}

static void PolySubtract(double[] p, double[] s) {
for (int i = 0; i < p.Length; ++i) {
p[i] -= s[i];
}
}

static Solution PolyLongDiv(double[] n, double[] d) {
if (n.Length != d.Length) {
throw new ArgumentException("Numerator and denominator vectors must have the same size");
}
int nd = PolyDegree(n);
int dd = PolyDegree(d);
if (dd < 0) {
throw new ArgumentException("Divisor must have at least one one-zero coefficient");
}
if (nd < dd) {
throw new ArgumentException("The degree of the divisor cannot exceed that of the numerator");
}
double[] n2 = new double[n.Length];
n.CopyTo(n2, 0);
double[] q = new double[n.Length];
while (nd >= dd) {
double[] d2 = PolyShiftRight(d, nd - dd);
q[nd - dd] = n2[nd] / d2[nd];
PolyMultiply(d2, q[nd - dd]);
PolySubtract(n2, d2);
nd = PolyDegree(n2);
}
return new Solution(q, n2);
}

static void PolyShow(double[] p) {
int pd = PolyDegree(p);
for (int i = pd; i >= 0; --i) {
double coeff = p[i];
if (coeff == 0.0) continue;
if (coeff == 1.0) {
if (i < pd) {
Console.Write(" + ");
}
} else if (coeff == -1.0) {
if (i < pd) {
Console.Write(" - ");
} else {
Console.Write("-");
}
} else if (coeff < 0.0) {
if (i < pd) {
Console.Write(" - {0:F1}", -coeff);
} else {
Console.Write("{0:F1}", coeff);
}
} else {
if (i < pd) {
Console.Write(" + {0:F1}", coeff);
} else {
Console.Write("{0:F1}", coeff);
}
}
if (i > 1) Console.Write("x^{0}", i);
else if (i == 1) Console.Write("x");
}
Console.WriteLine();
}

static void Main(string[] args) {
double[] n = { -42.0, 0.0, -12.0, 1.0 };
double[] d = { -3.0, 1.0, 0.0, 0.0 };
Console.Write("Numerator   : ");
PolyShow(n);
Console.Write("Denominator : ");
PolyShow(d);
Console.WriteLine("-------------------------------------");
Solution sol = PolyLongDiv(n, d);
Console.Write("Quotient    : ");
PolyShow(sol.Quotient);
Console.Write("Remainder   : ");
PolyShow(sol.Remainder);
}
}
}
Output:
Numerator   : x^3 - 12.0x^2 - 42.0
Denominator : x - 3.0
-------------------------------------
Quotient    : x^2 - 9.0x - 27.0
Remainder   : -123.0

## C++

#include <iostream>
#include <iterator>
#include <vector>

using namespace std;
typedef vector<double> Poly;

// does:  prints all members of vector
// input: c - ASCII char with the name of the vector
//        A - reference to polynomial (vector)
void Print(char name, const Poly &A) {
cout << name << "(" << A.size()-1 << ") = [ ";
copy(A.begin(), A.end(), ostream_iterator<decltype(A[0])>(cout, " "));
cout << "]\n";
}

int main() {
Poly N, D, d, q, r;        // vectors - N / D == q && N % D == r
size_t dN, dD, dd, dq, dr; // degrees of vectors
size_t i;                  // loop counter

// setting the degrees of vectors
cout << "Enter the degree of N: ";
cin >> dN;
cout << "Enter the degree of D: ";
cin >> dD;
dq = dN-dD;
dr = dN-dD;

if( dD < 1 || dN < 1 ) {
cerr << "Error: degree of D and N must be positive.\n";
return 1;
}

// allocation and initialization of vectors
N.resize(dN+1);
cout << "Enter the coefficients of N:"<<endl;
for ( i = 0; i <= dN; i++ ) {
cout << "N[" << i << "]= ";
cin >> N[i];
}

D.resize(dN+1);
cout << "Enter the coefficients of D:"<<endl;
for ( i = 0; i <= dD; i++ ) {
cout << "D[" << i << "]= ";
cin >> D[i];
}

d.resize(dN+1);
q.resize(dq+1);
r.resize(dr+1);

cout << "-- Procedure --" << endl << endl;
if( dN >= dD ) {
while(dN >= dD) {
// d equals D shifted right
d.assign(d.size(), 0);

for( i = 0 ; i <= dD ; i++ )
d[i+dN-dD] = D[i];
dd = dN;

Print( 'd', d );

// calculating one element of q
q[dN-dD] = N[dN]/d[dd];

Print( 'q', q );

// d equals d * q[dN-dD]
for( i = 0 ; i < dq + 1 ; i++ )
d[i] = d[i] * q[dN-dD];

Print( 'd', d );

// N equals N - d
for( i = 0 ; i < dN + 1 ; i++ )
N[i] = N[i] - d[i];
dN--;

Print( 'N', N );
cout << "-----------------------" << endl << endl;

}
}

// r equals N
for( i = 0 ; i <= dN ; i++ )
r[i] = N[i];

cout << "=========================" << endl << endl;
cout << "-- Result --" << endl << endl;

Print( 'q', q );
Print( 'r', r );
}

## Clojure

This example performs multivariate polynomial division using Buchberger's algorithm to decompose a polynomial into its Gröbner bases. Polynomials are represented as hash-maps of monomials with tuples of exponents as keys and their corresponding coefficients as values: e.g. 2xy + 3x + 5y + 7 is represented as {[1 1] 2, [1 0] 3, [0 1] 5, [0 0] 7}.

Since this algorithm is much more efficient when the input is in graded reverse lexicographic (grevlex) order a comparator is included to be used with Clojure's sorted-map—(into (sorted-map-by grevlex) ...)—as well as necessary functions to compute polynomial multiplication, monomial complements, and S-polynomials.

(defn grevlex [term1 term2]
(if (not= 0 comp)
comp
(loop [term1 term1
term2 term2]
(if (empty? term1)
0
comp (- grade1 grade2)] ;; differs from grlex because terms are flipped from above
(if (not= 0 comp)
comp
(recur (pop term1)
(pop term2)))))))))

(defn mul
;; transducer
([poly1]  ;; completion
(fn
([] poly1)
([poly2] (mul poly1 poly2))
([poly2 & more] (mul poly1 poly2 more))))
([poly1 poly2]
(let [product (atom (transient (sorted-map-by grevlex)))]
(doall  ;; for is lazy so must to be forced for side-effects
(for [term1 poly1
term2 poly2
:let [vars (mapv +' (key term1) (key term2))
coeff (* (val term1) (val term2))]]
(if (contains? @product vars)
(swap! product assoc! vars (+ (get @product vars) coeff))
(swap! product assoc! vars coeff))))
(->> product
(deref)
(persistent!)
(denull))))
([poly1 poly2 & more]
(reduce mul (mul poly1 poly2) more)))

(defn compl [term1 term2]
(map (fn [x y]
(cond
(and (zero? x) (not= 0 y)) nil
(< x y) nil
(>= x y) (- x y)))
term1
term2))

(defn s-poly [f g]
(let [f-vars (first f)
g-vars (first g)
lcm (compl f-vars g-vars)]
(if (not-any? nil? lcm)
{(vec lcm)
(/ (second f) (second g))})))

(defn divide [f g]
(loop [f f
g g
result (transient {})
remainder {}]
(if (empty? f)
(list (persistent! result)
(->> remainder
(filter #(not (nil? %)))
(into (sorted-map-by grevlex))))
(let [term1 (first f)
term2 (first g)
s-term (s-poly term1 term2)]
(if (nil? s-term)
(recur (dissoc f (first term1))
(dissoc g (first term2))
result
(conj remainder term1))
(recur (sub f (mul g s-term))
g
(conj! result s-term)
remainder))))))

(deftest divide-tests
(is (= (divide {[1 1] 2, [1 0] 3, [0 1] 5, [0 0] 7}
{[1 1] 2, [1 0] 3, [0 1] 5, [0 0] 7})
'({[0 0] 1} {})))
(is (= (divide {[1 1] 2, [1 0] 3, [0 1] 5, [0 0] 7}
{[0 0] 1})
'({[1 1] 2, [1 0] 3, [0 1] 5, [0 0] 7} {})))
(is (= (divide {[1 1] 2, [1 0] 10, [0 1] 3, [0 0] 15}
{[0 1] 1, [0 0] 5})
'({[1 0] 2, [0 0] 3} {})))
(is (= (divide {[1 1] 2, [1 0] 10, [0 1] 3, [0 0] 15}
{[1 0] 2, [0 0] 3})
'({[0 1] 1, [0 0] 5} {}))))

## Common Lisp

Polynomials are represented as lists of degree/coefficient pairs ordered by degree (highest degree first), and pairs with zero coefficients can be omitted. Multiply and divide perform long multiplication and long division, respectively. multiply returns one value, the product, and divide returns two, the quotient and the remainder.

(do ((sum '())) ((and (endp p1) (endp p2)) (nreverse sum))
(let ((pd1 (if (endp p1) -1 (caar p1)))
(pd2 (if (endp p2) -1 (caar p2))))
(multiple-value-bind (c1 c2)
(cond
((> pd1 pd2) (values (cdr (pop p1)) 0))
((< pd1 pd2) (values 0 (cdr (pop p2))))
(t  (values (cdr (pop p1)) (cdr (pop p2)))))
(let ((csum (+ c1 c2)))
(unless (zerop csum)
(setf sum (acons (max pd1 pd2) csum sum))))))))

(defun multiply (p1 p2)
(flet ((*p2 (p)
(destructuring-bind (d . c) p
(loop for (pd . pc) in p2
collecting (cons (+ d pd) (* c pc))))))
(reduce 'add (mapcar #'*p2 p1) :initial-value '())))

(defun subtract (p1 p2)
(add p1 (multiply '((0 . -1)) p2)))

(defun divide (dividend divisor &aux (sum '()))
(assert (not (endp divisor)) (divisor)
'division-by-zero
:operation 'divide
:operands (list dividend divisor))
(flet ((floor1 (dividend divisor)
(if (endp dividend) (values '() ())
(destructuring-bind (d1 . c1) (first dividend)
(destructuring-bind (d2 . c2) (first divisor)
(if (> d2 d1) (values '() dividend)
(let* ((quot (list (cons (- d1 d2) (/ c1 c2))))
(rem (subtract dividend (multiply divisor quot))))
(values quot rem))))))))
(loop (multiple-value-bind (quotient remainder)
(floor1 dividend divisor)
(if (endp quotient) (return (values sum remainder))
(setf dividend remainder
> (divide '((3 . 1) (2 . -12) (0 . -42)) ; x^3 - 12x^2 - 42
'((1 . 1) (0 . -3)))           ; x - 3
((2 . 1) (1 . -9) (0 . -27)) ; x^2 - 9x - 27
((0 . -123))                 ; -123

## D

import std.stdio, std.range, std.algorithm, std.typecons, std.conv;

Tuple!(double[], double[]) polyDiv(in double[] inN, in double[] inD)
nothrow pure @safe {
// Code smell: a function that does two things.
static int trimAndDegree(T)(ref T[] poly) nothrow pure @safe @nogc {
poly = poly.retro.find!q{ a != b }(0.0).retro;
return poly.length.signed - 1;
}

auto N = inN.dup;
const(double)[] D = inD;
const dD = trimAndDegree(D);
auto dN = trimAndDegree(N);
double[] q;
if (dD < 0)
throw new Error("ZeroDivisionError");
if (dN >= dD) {
q = [0.0].replicate(dN);
while (dN >= dD) {
auto d = [0.0].replicate(dN - dD) ~ D;
immutable mult = q[dN - dD] = N[$- 1] / d[$ - 1];
d[] *= mult;
N[] -= d[];
dN = trimAndDegree(N);
}
} else
q = [0.0];
return tuple(q, N);
}

int trimAndDegree1(T)(ref T[] poly) nothrow pure @safe @nogc {
poly.length -= poly.retro.countUntil!q{ a != 0 };
return poly.length.signed - 1;
}

void main() {
immutable N = [-42.0, 0.0, -12.0, 1.0];
immutable D = [-3.0, 1.0, 0.0, 0.0];
writefln("%s / %s = %s  remainder %s", N, D, polyDiv(N, D)[]);
}
Output:
[-42, 0, -12, 1] / [-3, 1, 0, 0] = [-27, -9, 1]  remainder [-123]

## Delphi

Translation of: C#
program Polynomial_long_division;

{$APPTYPE CONSOLE} uses System.SysUtils; type PPolySolution = ^TPolySolution; TPolynomio = record private class function Degree(p: TPolynomio): Integer; static; class function ShiftRight(p: TPolynomio; places: Integer): TPolynomio; static; class function PolyMultiply(p: TPolynomio; m: double): TPolynomio; static; class function PolySubtract(p, s: TPolynomio): TPolynomio; static; class function PolyLongDiv(n, d: TPolynomio): PPolySolution; static; function GetSize: Integer; public value: TArray<Double>; class operator RightShift(p: TPolynomio; b: Integer): TPolynomio; class operator Multiply(p: TPolynomio; m: double): TPolynomio; class operator Subtract(p, s: TPolynomio): TPolynomio; class operator Divide(p, s: TPolynomio): PPolySolution; class operator Implicit(a: TArray<Double>): TPolynomio; class operator Implicit(a: TPolynomio): string; procedure Assign(other: TPolynomio); overload; procedure Assign(other: TArray<Double>); overload; property Size: Integer read GetSize; function ToString: string; end; TPolySolution = record Quotient, Remainder: TPolynomio; constructor Create(q, r: TPolynomio); end; { TPolynomio } procedure TPolynomio.Assign(other: TPolynomio); begin Assign(other.value); end; procedure TPolynomio.Assign(other: TArray<Double>); begin SetLength(value, length(other)); for var i := 0 to High(other) do value[i] := other[i]; end; class function TPolynomio.Degree(p: TPolynomio): Integer; begin var len := high(p.value); for var i := len downto 0 do begin if p.value[i] <> 0.0 then exit(i); end; Result := -1; end; class operator TPolynomio.Divide(p, s: TPolynomio): PPolySolution; begin Result := PolyLongDiv(p, s); end; function TPolynomio.GetSize: Integer; begin Result := Length(value); end; class operator TPolynomio.Implicit(a: TPolynomio): string; begin Result := a.toString; end; class operator TPolynomio.Implicit(a: TArray<Double>): TPolynomio; begin Result.Assign(a); end; class operator TPolynomio.Multiply(p: TPolynomio; m: double): TPolynomio; begin Result := TPolynomio.PolyMultiply(p, m); end; class function TPolynomio.PolyLongDiv(n, d: TPolynomio): PPolySolution; var Solution: TPolySolution; begin if length(n.value) <> Length(d.value) then raise Exception.Create('Numerator and denominator vectors must have the same size'); var nd := Degree(n); var dd := Degree(d); if dd < 0 then raise Exception.Create('Divisor must have at least one one-zero coefficient'); if nd < dd then raise Exception.Create('The degree of the divisor cannot exceed that of the numerator'); var n2, q: TPolynomio; n2.Assign(n); SetLength(q.value, length(n.value)); while nd >= dd do begin var d2 := d shr (nd - dd); q.value[nd - dd] := n2.value[nd] / d2.value[nd]; d2 := d2 * q.value[nd - dd]; n2 := n2 - d2; nd := Degree(n2); end; new(Result); Result^.Create(q, n2); end; class function TPolynomio.PolyMultiply(p: TPolynomio; m: double): TPolynomio; begin Result.Assign(p); for var i := 0 to High(p.value) do Result.value[i] := p.value[i] * m; end; class operator TPolynomio.RightShift(p: TPolynomio; b: Integer): TPolynomio; begin Result := TPolynomio.ShiftRight(p, b); end; class function TPolynomio.ShiftRight(p: TPolynomio; places: Integer): TPolynomio; begin Result.Assign(p); if places <= 0 then exit; var pd := Degree(p); Result.Assign(p); for var i := pd downto 0 do begin Result.value[i + places] := Result.value[i]; Result.value[i] := 0.0; end; end; class operator TPolynomio.Subtract(p, s: TPolynomio): TPolynomio; begin Result := TPolynomio.PolySubtract(p, s); end; class function TPolynomio.PolySubtract(p, s: TPolynomio): TPolynomio; begin Result.Assign(p); for var i := 0 to High(p.value) do Result.value[i] := p.value[i] - s.value[i]; end; function TPolynomio.ToString: string; begin Result := ''; var pd := Degree(self); for var i := pd downto 0 do begin var coeff := value[i]; if coeff = 0.0 then Continue; if coeff = 1.0 then begin if i < pd then Result := Result + ' + '; end else begin if coeff = -1 then begin if i < pd then Result := Result + ' - ' else Result := Result + '-'; end else begin if coeff < 0.0 then begin if i < pd then Result := Result + format(' - %.1f', [-coeff]) else Result := Result + format('%.1f', [coeff]); end else begin if i < pd then Result := Result + format(' + %.1f', [coeff]) else Result := Result + format('%.1f', [coeff]); end; end; end; if i > 1 then Result := Result + 'x^' + i.tostring else if i = 1 then Result := Result + 'x'; end; end; { TPolySolution } constructor TPolySolution.Create(q, r: TPolynomio); begin Quotient.Assign(q); Remainder.Assign(r); end; // Just for force implicitty string conversion procedure Writeln(s: string); begin System.Writeln(s); end; var n, d: TPolynomio; Solution: PPolySolution; begin n := [-42.0, 0.0, -12.0, 1.0]; d := [-3.0, 1.0, 0.0, 0.0]; Write('Numerator : '); Writeln(n); Write('Denominator : '); Writeln(d); Writeln('-------------------------------------'); Solution := n / d; Write('Quotient : '); Writeln(Solution^.Quotient); Write('Remainder : '); Writeln(Solution^.Remainder); FreeMem(Solution, sizeof(TPolySolution)); Readln; end. ## E  Some lines in this example are too long (more than 80 characters). Please fix the code if it's possible and remove this message. This program has some unnecessary features contributing to its length: • It creates polynomial objects rather than performing its operations directly on arrays. • It includes code for printing polynomials nicely. • It prints the intermediate steps of the division. pragma.syntax("0.9") pragma.enable("accumulator") def superscript(x, out) { if (x >= 10) { superscript(x // 10) } out.print("⁰¹²³⁴⁵⁶⁷⁸⁹"[x %% 10]) } def makePolynomial(initCoeffs :List) { def degree := { var i := initCoeffs.size() - 1 while (i >= 0 && initCoeffs[i] <=> 0) { i -= 1 } if (i < 0) { -Infinity } else { i } } def coeffs := initCoeffs(0, if (degree == -Infinity) { [] } else { degree + 1 }) def polynomial { /** Print the polynomial (not necessary for the task) */ to __printOn(out) { out.print("(λx.") var first := true for i in (0..!(coeffs.size())).descending() { def coeff := coeffs[i] if (coeff <=> 0) { continue } out.print(" ") if (coeff <=> 1 && !(i <=> 0)) { # no coefficient written if it's 1 and not the constant term } else if (first) { out.print(coeff) } else if (coeff > 0) { out.print("+ ", coeff) } else { out.print("- ", -coeff) } if (i <=> 0) { # no x if it's the constant term } else if (i <=> 1) { out.print("x") } else { out.print("x"); superscript(i, out) } first := false } out.print(")") } /** Evaluate the polynomial (not necessary for the task) */ to run(x) { return accum 0 for i => c in coeffs { _ + c * x**i } } to degree() { return degree } to coeffs() { return coeffs } to highestCoeff() { return coeffs[degree] } /** Could support another polynomial, but not part of this task. Computes this * x**power. */ to timesXToThe(power) { return makePolynomial([0] * power + coeffs) } /** Multiply (by a scalar only). */ to multiply(scalar) { return makePolynomial(accum [] for x in coeffs { _.with(x * scalar) }) } /** Subtract (by another polynomial only). */ to subtract(other) { def oc := other.coeffs() :List return makePolynomial(accum [] for i in 0..(coeffs.size().max(oc.size())) { _.with(coeffs.fetch(i, fn{0}) - oc.fetch(i, fn{0})) }) } /** Polynomial long division. */ to quotRem(denominator, trace) { var numerator := polynomial require(denominator.degree() >= 0) if (numerator.degree() < denominator.degree()) { return [makePolynomial([]), denominator] } else { var quotientCoeffs := [0] * (numerator.degree() - denominator.degree()) while (numerator.degree() >= denominator.degree()) { trace.print(" ", numerator, "\n") def qCoeff := numerator.highestCoeff() / denominator.highestCoeff() def qPower := numerator.degree() - denominator.degree() quotientCoeffs with= (qPower, qCoeff) def d := denominator.timesXToThe(qPower) * qCoeff trace.print("- ", d, " (= ", denominator, " * ", qCoeff, "x"); superscript(qPower, trace); trace.print(")\n") numerator -= d trace.print(" -------------------------- (Quotient so far: ", makePolynomial(quotientCoeffs), ")\n") } return [makePolynomial(quotientCoeffs), numerator] } } } return polynomial } def n := makePolynomial([-42, 0, -12, 1]) def d := makePolynomial([-3, 1]) println("Numerator: ", n) println("Denominator: ", d) def [q, r] := n.quotRem(d, stdout) println("Quotient: ", q) println("Remainder: ", r) Output: Numerator: (λx. x³ - 12x² - 42) Denominator: (λx. x - 3) (λx. x³ - 12x² - 42) - (λx. x³ - 3.0x²) (= (λx. x - 3) * 1.0x²) -------------------------- (Quotient so far: (λx. x²)) (λx. -9.0x² - 42.0) - (λx. -9.0x² + 27.0x) (= (λx. x - 3) * -9.0x¹) -------------------------- (Quotient so far: (λx. x² - 9.0x)) (λx. -27.0x - 42.0) - (λx. -27.0x + 81.0) (= (λx. x - 3) * -27.0x⁰) -------------------------- (Quotient so far: (λx. x² - 9.0x - 27.0)) Quotient: (λx. x² - 9.0x - 27.0) Remainder: (λx. -123.0) ## Elixir Translation of: Ruby defmodule Polynomial do def division(_, []), do: raise ArgumentError, "denominator is zero" def division(_, [0]), do: raise ArgumentError, "denominator is zero" def division(f, g) when length(f) < length(g), do: {[0], f} def division(f, g) do {q, r} = division(g, [], f) if q==[], do: q = [0] if r==[], do: r = [0] {q, r} end defp division(g, q, r) when length(r) < length(g), do: {q, r} defp division(g, q, r) do p = hd(r) / hd(g) r2 = Enum.zip(r, g) |> Enum.with_index |> Enum.reduce(r, fn {{pn,pg},i},acc -> List.replace_at(acc, i, pn - p * pg) end) division(g, q++[p], tl(r2)) end end [ { [1, -12, 0, -42], [1, -3] }, { [1, -12, 0, -42], [1, 1, -3] }, { [1, 3, 2], [1, 1] }, { [1, -4, 6, 5, 3], [1, 2, 1] } ] |> Enum.each(fn {f,g} -> {q, r} = Polynomial.division(f, g) IO.puts "#{inspect f} / #{inspect g} => #{inspect q} remainder #{inspect r}" end) Output: [1, -12, 0, -42] / [1, -3] => [1.0, -9.0, -27.0] remainder [-123.0] [1, -12, 0, -42] / [1, 1, -3] => [1.0, -13.0] remainder [16.0, -81.0] [1, 3, 2] / [1, 1] => [1.0, 2.0] remainder [0.0] [1, -4, 6, 5, 3] / [1, 2, 1] => [1.0, -6.0, 17.0] remainder [-23.0, -14.0] ## F# Translation of: Ocaml let rec shift n l = if n <= 0 then l else shift (n-1) (l @ [0.0]) let rec pad n l = if n <= 0 then l else pad (n-1) (0.0 :: l) let rec norm = function | 0.0 :: tl -> norm tl | x -> x let deg l = List.length (norm l) - 1 let zip op p q = let d = (List.length p) - (List.length q) in List.map2 op (pad (-d) p) (pad d q) let polydiv f g = let rec aux f s q = let ddif = (deg f) - (deg s) in if ddif < 0 then (q, f) else let k = (List.head f) / (List.head s) in let ks = List.map ((*) k) (shift ddif s) in let q' = zip (+) q (shift ddif [k]) let f' = norm (List.tail (zip (-) f ks)) in aux f' s q' in aux (norm f) (norm g) [] let str_poly l = let term v p = match (v, p) with | ( _, 0) -> string v | (1.0, 1) -> "x" | ( _, 1) -> (string v) + "*x" | (1.0, _) -> "x^" + (string p) | _ -> (string v) + "*x^" + (string p) in let rec terms = function | [] -> [] | h :: t -> if h = 0.0 then (terms t) else (term h (List.length t)) :: (terms t) in String.concat " + " (terms l) let _ = let f,g = [1.0; -4.0; 6.0; 5.0; 3.0], [1.0; 2.0; 1.0] in let q, r = polydiv f g in Printf.printf " (%s) div (%s)\ngives\nquotient:\t(%s)\nremainder:\t(%s)\n" (str_poly f) (str_poly g) (str_poly q) (str_poly r) Output: (x^4 + -4*x^3 + 6*x^2 + 5*x + 3) div (x^2 + 2*x + 1) gives quotient: (x^2 + -6*x + 17) remainder: (-23*x + -14) ## Factor USE: math.polynomials { -42 0 -12 1 } { -3 1 } p/mod ptrim [ . ] bi@ Output: V{ -27 -9 1 } V{ -123 } ## Fortran Works with: Fortran version 95 and later module Polynom implicit none contains subroutine poly_long_div(n, d, q, r) real, dimension(:), intent(in) :: n, d real, dimension(:), intent(out), allocatable :: q real, dimension(:), intent(out), allocatable, optional :: r real, dimension(:), allocatable :: nt, dt, rt integer :: gn, gt, gd if ( (size(n) >= size(d)) .and. (size(d) > 0) .and. (size(n) > 0) ) then allocate(nt(size(n)), dt(size(n)), rt(size(n))) nt = n dt = 0 dt(1:size(d)) = d rt = 0 gn = size(n)-1 gd = size(d)-1 gt = 0 do while ( d(gd+1) == 0 ) gd = gd - 1 end do do while( gn >= gd ) dt = eoshift(dt, -(gn-gd)) rt(gn-gd+1) = nt(gn+1) / dt(gn+1) nt = nt - dt * rt(gn-gd+1) gt = max(gt, gn-gd) do gn = gn - 1 if ( nt(gn+1) /= 0 ) exit end do dt = 0 dt(1:size(d)) = d end do allocate(q(gt+1)) q = rt(1:gt+1) if ( present(r) ) then if ( (gn+1) > 0 ) then allocate(r(gn+1)) r = nt(1:gn+1) else allocate(r(1)) r = 0.0 end if end if deallocate(nt, dt, rt) else allocate(q(1)) q = 0 if ( present(r) ) then allocate(r(size(n))) r = n end if end if end subroutine poly_long_div subroutine poly_print(p) real, dimension(:), intent(in) :: p integer :: i do i = size(p), 1, -1 if ( i > 1 ) then write(*, '(F0.2,"x^",I0," + ")', advance="no") p(i), i-1 else write(*, '(F0.2)') p(i) end if end do end subroutine poly_print end module Polynom program PolyDivTest use Polynom implicit none real, dimension(:), allocatable :: q real, dimension(:), allocatable :: r !! three tests from Wikipedia, plus an extra !call poly_long_div( (/ -3., 1. /), (/ -42., 0.0, -12., 1. /), q, r) call poly_long_div( (/ -42., 0.0, -12., 1. /), (/ -3., 1. /), q, r) !call poly_long_div( (/ -42., 0.0, -12., 1. /), (/ -3., 1., 1. /), q, r) !call poly_long_div( (/ 2., 3., 1. /), (/ 1., 1. /), q, r) call poly_print(q) call poly_print(r) deallocate(q, r) end program PolyDivTest ## FreeBASIC #define EPS 1.0e-20 type polyterm degree as uinteger coeff as double end type sub poly_print( P() as double ) dim as string outstr = "", sri for i as integer = ubound(P) to 0 step -1 if outstr<>"" then if P(i)>0 then outstr = outstr + " + " if P(i)<0 then outstr = outstr + " - " end if if P(i)=0 then continue for if abs(P(i))<>1 or i=0 then if outstr="" then outstr = outstr + str((P(i))) else outstr = outstr + str(abs(P(i))) end if end if if i>0 then outstr=outstr+"x" sri= str(i) if i>1 then outstr=outstr + "^" + sri next i print outstr end sub function lc_deg( B() as double ) as polyterm 'gets the coefficent and degree of the leading term in a polynomial dim as polyterm ret for i as uinteger = ubound(B) to 0 step -1 if B(i)<>0 then ret.degree = i ret.coeff = B(i) return ret end if next i return ret end function sub poly_multiply( byval k as polyterm, P() as double ) 'in-place multiplication of polynomial by a polynomial term dim i as integer for i = ubound(P) to k.degree step -1 P(i) = k.coeff*P(i-k.degree) next i for i = k.degree-1 to 0 step -1 P(i)=0 next i end sub sub poly_subtract( P() as double, Q() as double ) 'in place subtraction of one polynomial from another dim as uinteger deg = ubound(P) for i as uinteger = 0 to deg P(i) -= Q(i) if abs(P(i))<EPS then P(i)=0 'stupid floating point subtraction, grumble grumble next i end sub sub poly_add( P() as double, byval t as polyterm ) 'in-place addition of a polynomial term to a polynomial P(t.degree) += t.coeff end sub sub poly_copy( source() as double, target() as double ) for i as uinteger = 0 to ubound(source) target(i) = source(i) next i end sub sub polydiv( A() as double, B() as double, Q() as double, R() as double ) dim as polyterm s dim as double sB(0 to ubound(B)) poly_copy A(), R() dim as uinteger d = ubound(B), degr = lc_deg(R()).degree dim as double c = lc_deg(B()).coeff while degr >= d s.coeff = lc_deg(R()).coeff/c s.degree = degr - d poly_add Q(), s poly_copy B(), sB() redim preserve sB(0 to s.degree+ubound(sB)) as double poly_multiply s, sB() poly_subtract R(), sB() degr = lc_deg(R()).degree redim sB(0 to ubound(B)) wend end sub dim as double N(0 to 4) = {-42, 0, -12, 1} 'x^3 - 12x^2 - 42 dim as double D(0 to 2) = {-3, 1} ' x - 3 dim as double Q(0 to ubound(N)), R(0 to ubound(N)) polydiv( N(), D(), Q(), R() ) poly_print Q() 'quotient poly_print R() 'remainder Output: x^2 - 9x - 27 -123 ## GAP GAP has built-in functions for computations with polynomials. x := Indeterminate(Rationals, "x"); p := x^11 + 3*x^8 + 7*x^2 + 3; q := x^7 + 5*x^3 + 1; QuotientRemainder(p, q); # [ x^4+3*x-5, -16*x^4+25*x^3+7*x^2-3*x+8 ] ## Go By the convention and pseudocode given in the task: package main import "fmt" func main() { n := []float64{-42, 0, -12, 1} d := []float64{-3, 1} fmt.Println("N:", n) fmt.Println("D:", d) q, r, ok := pld(n, d) if ok { fmt.Println("Q:", q) fmt.Println("R:", r) } else { fmt.Println("error") } } func degree(p []float64) int { for d := len(p) - 1; d >= 0; d-- { if p[d] != 0 { return d } } return -1 } func pld(nn, dd []float64) (q, r []float64, ok bool) { if degree(dd) < 0 { return } nn = append(r, nn...) if degree(nn) >= degree(dd) { q = make([]float64, degree(nn)-degree(dd)+1) for degree(nn) >= degree(dd) { d := make([]float64, degree(nn)+1) copy(d[degree(nn)-degree(dd):], dd) q[degree(nn)-degree(dd)] = nn[degree(nn)] / d[degree(d)] for i := range d { d[i] *= q[degree(nn)-degree(dd)] nn[i] -= d[i] } } } return q, nn, true } Output: N: [-42 0 -12 1] D: [-3 1] Q: [-27 -9 1] R: [-123 0 0 0] ## Haskell Translated from the OCaml code elsewhere on the page. Works with: GHC version 6.10 import Data.List shift n l = l ++ replicate n 0 pad n l = replicate n 0 ++ l norm :: Fractional a => [a] -> [a] norm = dropWhile (== 0) deg l = length (norm l) - 1 zipWith' op p q = zipWith op (pad (-d) p) (pad d q) where d = (length p) - (length q) polydiv f g = aux (norm f) (norm g) [] where aux f s q | ddif < 0 = (q, f) | otherwise = aux f' s q' where ddif = (deg f) - (deg s) k = (head f) / (head s) ks = map (* k)$ shift ddif s
q' = zipWith' (+) q $shift ddif [k] f' = norm$ tail $zipWith' (-) f ks And this is the also-translated pretty printing function. str_poly l = intercalate " + "$ terms l
where term v 0 = show v
term 1 1 = "x"
term v 1 = (show v) ++ "x"
term 1 p = "x^" ++ (show p)
term v p = (show v) ++ "x^" ++ (show p)

terms :: Fractional a => [a] -> [String]
terms [] = []
terms (0:t) = terms t
terms (h:t) = (term h (length t)) : (terms t)

## J

divmod=:[: (}: ; {:) ([ (] -/@,:&}. (* {:)) ] , %&{.~)^:(>:@-~&#)&.|.~

Wikipedia example:

_42 0 _12 1 divmod _3 1

This produces the result:

┌────────┬────┐
│_27 _9 1│_123│
└────────┴────┘

This means that ${\displaystyle -42-12x^{2}+x^{3}}$ divided by ${\displaystyle -3+x}$ produces ${\displaystyle -27-9x+x^{2}}$ with a remainder of ${\displaystyle -123}$.

## Java

Replace existing translation.

When generalized, the coefficients of polynomial division are fractions. This implementation supports integer and fraction coefficients.

To test and validate the results, polynomial multiplication and addition are also implemented.

import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

public class PolynomialLongDivision {

public static void main(String[] args) {
RunDivideTest(new Polynomial(1, 3, -12, 2, -42, 0), new Polynomial(1, 1, -3, 0));
RunDivideTest(new Polynomial(5, 2, 4, 1, 1, 0), new Polynomial(2, 1, 3, 0));
RunDivideTest(new Polynomial(5, 10, 4, 7, 1, 0), new Polynomial(2, 4, 2, 2, 3, 0));
RunDivideTest(new Polynomial(2,7,-24,6,2,5,-108,4,3,3,-120,2,-126,0), new Polynomial(2, 4, 2, 2, 3, 0));
}

private static void RunDivideTest(Polynomial p1, Polynomial p2) {
Polynomial[] result = p1.divide(p2);
System.out.printf("Compute: (%s) / (%s) = %s reminder %s%n", p1, p2, result[0], result[1]);
System.out.printf("Test:    (%s) * (%s) + (%s) = %s%n%n", result[0], p2, result[1], result[0].multiply(p2).add(result[1]));
}

private static final class Polynomial {

private List<Term> polynomialTerms;

//  Format - coeff, exp, coeff, exp, (repeating in pairs) . . .
public Polynomial(long ... values) {
if ( values.length % 2 != 0 ) {
throw new IllegalArgumentException("ERROR 102:  Polynomial constructor.  Length must be even.  Length = " + values.length);
}
polynomialTerms = new ArrayList<>();
for ( int i = 0 ; i < values.length ; i += 2 ) {
}
Collections.sort(polynomialTerms, new TermSorter());
}

public Polynomial() {
//  zero
polynomialTerms = new ArrayList<>();
}

private Polynomial(List<Term> termList) {
if ( termList.size() != 0 ) {
//  Remove zero terms if needed
for ( int i = 0 ; i < termList.size() ; i++ ) {
if ( termList.get(i).coefficient.compareTo(Integer.ZERO_INT) == 0 ) {
termList.remove(i);
}
}
}
if ( termList.size() == 0 ) {
//  zero
}
polynomialTerms = termList;
Collections.sort(polynomialTerms, new TermSorter());
}

public Polynomial[] divide(Polynomial v) {
Polynomial q = new Polynomial();
Polynomial r = this;
long dv = v.degree();
while ( r.degree() >= dv ) {
Number s = lcr.divide(lcv);
Term term = new Term(s, r.degree() - dv);
}
return new Polynomial[] {q, r};
}

List<Term> termList = new ArrayList<>();
int thisCount = polynomialTerms.size();
int polyCount = polynomial.polynomialTerms.size();
while ( thisCount > 0 || polyCount > 0 ) {
Term thisTerm = thisCount == 0 ? null : polynomialTerms.get(thisCount-1);
Term polyTerm = polyCount == 0 ? null : polynomial.polynomialTerms.get(polyCount-1);
if ( thisTerm == null ) {
polyCount--;
}
else if (polyTerm == null ) {
thisCount--;
}
else if ( thisTerm.degree() == polyTerm.degree() ) {
if ( t.coefficient.compareTo(Integer.ZERO_INT) != 0 ) {
}
thisCount--;
polyCount--;
}
else if ( thisTerm.degree() < polyTerm.degree() ) {
thisCount--;
}
else {
polyCount--;
}
}
return new Polynomial(termList);
}

List<Term> termList = new ArrayList<>();
for ( int index = 0 ; index < polynomialTerms.size() ; index++ ) {
Term currentTerm = polynomialTerms.get(index);
if ( currentTerm.exponent == term.exponent ) {
if ( currentTerm.coefficient.add(term.coefficient).compareTo(Integer.ZERO_INT) != 0 ) {
}
}
else {
}
}
if ( ! added ) {
}
return new Polynomial(termList);
}

public Polynomial multiply(Polynomial polynomial) {
List<Term> termList = new ArrayList<>();
for ( int i = 0 ; i < polynomialTerms.size() ; i++ ) {
Term ci = polynomialTerms.get(i);
for ( int j = 0 ; j < polynomial.polynomialTerms.size() ; j++ ) {
Term cj = polynomial.polynomialTerms.get(j);
Term currentTerm = ci.multiply(cj);
for ( int k = 0 ; k < termList.size() ; k++ ) {
if ( currentTerm.exponent == termList.get(k).exponent ) {
if ( t.coefficient.compareTo(Integer.ZERO_INT) != 0 ) {
}
break;
}
}
if ( ! added ) {
}
}
}
return new Polynomial(termList);
}

public Polynomial multiply(Term term) {
List<Term> termList = new ArrayList<>();
for ( int index = 0 ; index < polynomialTerms.size() ; index++ ) {
Term currentTerm = polynomialTerms.get(index);
}
return new Polynomial(termList);
}

return polynomialTerms.get(0).coefficient;
}

public long degree() {
return polynomialTerms.get(0).exponent;
}

@Override
public String toString() {
StringBuilder sb = new StringBuilder();
boolean first = true;
for ( Term term : polynomialTerms ) {
if ( first ) {
sb.append(term);
first = false;
}
else {
sb.append(" ");
if ( term.coefficient.compareTo(Integer.ZERO_INT) > 0 ) {
sb.append("+ ");
sb.append(term);
}
else {
sb.append("- ");
sb.append(term.negate());
}
}
}
return sb.toString();
}
}

private static final class TermSorter implements Comparator<Term> {
@Override
public int compare(Term o1, Term o2) {
return (int) (o2.exponent - o1.exponent);
}
}

private static final class Term {
Number coefficient;
long exponent;

public Term(BigInteger c, long e) {
coefficient = new Integer(c);
exponent = e;
}

public Term(Number c, long e) {
coefficient = c;
exponent = e;
}

public Term multiply(Term term) {
return new Term(coefficient.multiply(term.coefficient), exponent + term.exponent);
}

if ( exponent != term.exponent ) {
throw new RuntimeException("ERROR 102:  Exponents not equal.");
}
}

public Term negate() {
return new Term(coefficient.negate(), exponent);
}

public long degree() {
return exponent;
}

@Override
public String toString() {
if ( coefficient.compareTo(Integer.ZERO_INT) == 0 ) {
return "0";
}
if ( exponent == 0 ) {
return "" + coefficient;
}
if ( coefficient.compareTo(Integer.ONE_INT) == 0 ) {
if ( exponent == 1 ) {
return "x";
}
else {
return "x^" + exponent;
}
}
if ( exponent == 1 ) {
return coefficient + "x";
}
return coefficient + "x^" + exponent;
}
}

private static abstract class Number {
public abstract int compareTo(Number in);
public abstract Number negate();
public abstract Number multiply(Number in);
public abstract Number inverse();
public abstract boolean isInteger();
public abstract boolean isFraction();

public Number subtract(Number in) {
}

public Number divide(Number in) {
return multiply(in.inverse());
}
}

public static class Fraction extends Number {

private final Integer numerator;
private final Integer denominator;

public Fraction(Integer n, Integer d) {
numerator = n;
denominator = d;
}

@Override
public int compareTo(Number in) {
if ( in.isInteger() ) {
Integer result = ((Integer) in).multiply(denominator);
return numerator.compareTo(result);
}
else if ( in.isFraction() ) {
Fraction inFrac = (Fraction) in;
Integer left = numerator.multiply(inFrac.denominator);
Integer right = denominator.multiply(inFrac.numerator);
return left.compareTo(right);
}
throw new RuntimeException("ERROR:  Unknown number type in Fraction.compareTo");
}

@Override
public Number negate() {
if ( denominator.integer.signum() < 0 ) {
return new Fraction(numerator, (Integer) denominator.negate());
}
return new Fraction((Integer) numerator.negate(), denominator);
}

@Override
if ( in.isInteger() ) {
//x/y+z = (x+yz)/y
return new Fraction((Integer) ((Integer) in).multiply(denominator).add(numerator), denominator);
}
else if ( in.isFraction() ) {
Fraction inFrac = (Fraction) in;
//  compute a/b + x/y
//  Let q = gcd(b,y)
//  Result = ( (a*y + x*b)/q ) / ( b*y/q )
Integer x = inFrac.numerator;
Integer y = inFrac.denominator;
Integer q = y.gcd(denominator);
Integer temp1 = numerator.multiply(y);
Integer temp2 = denominator.multiply(x);
Integer newDenom = denominator.multiply(y).divide(q);
if ( newDenom.compareTo(Integer.ONE_INT) == 0 ) {
}
Integer gcd2 = newDenom.gcd(newNum);
if ( gcd2.compareTo(Integer.ONE_INT) == 0 ) {
return new Fraction(newNum, newDenom);
}
newNum = newNum.divide(gcd2);
newDenom = newDenom.divide(gcd2);
if ( newDenom.compareTo(Integer.ONE_INT) == 0 ) {
return newNum;
}
else if ( newDenom.compareTo(Integer.MINUS_ONE_INT) == 0 ) {
return newNum.negate();
}
return new Fraction(newNum, newDenom);
}
throw new RuntimeException("ERROR:  Unknown number type in Fraction.compareTo");
}

@Override
public Number multiply(Number in) {
if ( in.isInteger() ) {
//x/y*z = x*z/y
Integer temp = numerator.multiply((Integer) in);
Integer gcd = temp.gcd(denominator);
if ( gcd.compareTo(Integer.ONE_INT) == 0 || gcd.compareTo(Integer.MINUS_ONE_INT) == 0 ) {
return new Fraction(temp, denominator);
}
Integer newTop = temp.divide(gcd);
Integer newBot = denominator.divide(gcd);
if ( newBot.compareTo(Integer.ONE_INT) == 0 ) {
return newTop;
}
if ( newBot.compareTo(Integer.MINUS_ONE_INT) == 0 ) {
return newTop.negate();
}
return new Fraction(newTop, newBot);
}
else if ( in.isFraction() ) {
Fraction inFrac = (Fraction) in;
//  compute a/b * x/y
Integer tempTop = numerator.multiply(inFrac.numerator);
Integer tempBot = denominator.multiply(inFrac.denominator);
Integer gcd = tempTop.gcd(tempBot);
if ( gcd.compareTo(Integer.ONE_INT) == 0 || gcd.compareTo(Integer.MINUS_ONE_INT) == 0 ) {
return new Fraction(tempTop, tempBot);
}
Integer newTop = tempTop.divide(gcd);
Integer newBot = tempBot.divide(gcd);
if ( newBot.compareTo(Integer.ONE_INT) == 0 ) {
return newTop;
}
if ( newBot.compareTo(Integer.MINUS_ONE_INT) == 0 ) {
return newTop.negate();
}
return new Fraction(newTop, newBot);
}
throw new RuntimeException("ERROR:  Unknown number type in Fraction.compareTo");
}

@Override
public boolean isInteger() {
return false;
}

@Override
public boolean isFraction() {
return true;
}

@Override
public String toString() {
return numerator.toString() + "/" + denominator.toString();
}

@Override
public Number inverse() {
if ( numerator.equals(Integer.ONE_INT) ) {
return denominator;
}
else if ( numerator.equals(Integer.MINUS_ONE_INT) ) {
return denominator.negate();
}
else if ( numerator.integer.signum() < 0 ) {
return new Fraction((Integer) denominator.negate(), (Integer) numerator.negate());
}
return new Fraction(denominator, numerator);
}
}

public static class Integer extends Number {

private BigInteger integer;
public static final Integer MINUS_ONE_INT = new Integer(new BigInteger("-1"));
public static final Integer ONE_INT = new Integer(new BigInteger("1"));
public static final Integer ZERO_INT = new Integer(new BigInteger("0"));

public Integer(BigInteger number) {
this.integer = number;
}

public int compareTo(Integer val) {
return integer.compareTo(val.integer);
}

@Override
public int compareTo(Number in) {
if ( in.isInteger() ) {
return compareTo((Integer) in);
}
else if ( in.isFraction() ) {
Fraction frac = (Fraction) in;
BigInteger result = integer.multiply(frac.denominator.integer);
return result.compareTo(frac.numerator.integer);
}
throw new RuntimeException("ERROR:  Unknown number type in Integer.compareTo");
}

@Override
public Number negate() {
return new Integer(integer.negate());
}

}

@Override
if ( in.isInteger() ) {
}
else if ( in.isFraction() ) {
Fraction f = (Fraction) in;
Integer top = f.numerator;
Integer bot = f.denominator;
}
throw new RuntimeException("ERROR:  Unknown number type in Integer.add");
}

@Override
public Number multiply(Number in) {
if ( in.isInteger() ) {
return multiply((Integer) in);
}
else if ( in.isFraction() ) {
//  a * x/y = ax/y
Integer x = ((Fraction) in).numerator;
Integer y = ((Fraction) in).denominator;
Integer temp = (Integer) multiply(x);
Integer gcd = temp.gcd(y);
if ( gcd.compareTo(Integer.ONE_INT) == 0 || gcd.compareTo(Integer.MINUS_ONE_INT) == 0 ) {
return new Fraction(temp, y);
}
Integer newTop = temp.divide(gcd);
Integer newBot = y.divide(gcd);
if ( newBot.compareTo(Integer.ONE_INT) == 0 ) {
return newTop;
}
if ( newBot.compareTo(Integer.MINUS_ONE_INT) == 0 ) {
return newTop.negate();
}
return new Fraction(newTop, newBot);
}
throw new RuntimeException("ERROR:  Unknown number type in Integer.add");
}

public Integer gcd(Integer in) {
return new Integer(integer.gcd(in.integer));
}

public Integer divide(Integer in) {
return new Integer(integer.divide(in.integer));
}

public Integer multiply(Integer in) {
return new Integer(integer.multiply(in.integer));
}

@Override
public boolean isInteger() {
return true;
}

@Override
public boolean isFraction() {
return false;
}

@Override
public String toString() {
return integer.toString();
}

@Override
public Number inverse() {
if ( equals(ZERO_INT) ) {
throw new RuntimeException("Attempting to take the inverse of zero in IntegerExpression");
}
else if ( this.compareTo(ONE_INT) == 0 ) {
return ONE_INT;
}
else if ( this.compareTo(MINUS_ONE_INT) == 0 ) {
return MINUS_ONE_INT;
}
return new Fraction(ONE_INT, this);
}

}
}
Output:
Compute: (x^3 - 12x^2 - 42) / (x - 3) = x^2 - 9x - 27 reminder -123
Test:    (x^2 - 9x - 27) * (x - 3) + (-123) = x^3 - 12x^2 - 42

Compute: (5x^2 + 4x + 1) / (2x + 3) = 5/2x - 7/4 reminder 25/4
Test:    (5/2x - 7/4) * (2x + 3) + (25/4) = 5x^2 + 4x + 1

Compute: (5x^10 + 4x^7 + 1) / (2x^4 + 2x^2 + 3) = 5/2x^6 - 5/2x^4 + 2x^3 - 5/4x^2 - 2x + 5 reminder -2x^3 - 25/4x^2 + 6x - 14
Test:    (5/2x^6 - 5/2x^4 + 2x^3 - 5/4x^2 - 2x + 5) * (2x^4 + 2x^2 + 3) + (-2x^3 - 25/4x^2 + 6x - 14) = 5x^10 + 4x^7 + 1

Compute: (2x^7 - 24x^6 + 2x^5 - 108x^4 + 3x^3 - 120x^2 - 126) / (2x^4 + 2x^2 + 3) = x^3 - 12x^2 - 42 reminder 0
Test:    (x^3 - 12x^2 - 42) * (2x^4 + 2x^2 + 3) + (0) = 2x^7 - 24x^6 + 2x^5 - 108x^4 + 3x^3 - 120x^2 - 126

## jq

Works with: jq

Also works with gojq, the Go implementation of jq, and with fq

Adapted from the second version in the Wren entry.

In this entry, polynomials are represented by JSON arrays exactly as in the task description; that is, using jq notation, .[$i] corresponds to the coefficient of {\displaystyle x^i}. # Emit the canonical form of the polynomical represented by the input array def canonical: if length == 0 then . elif .[-1] == 0 then .[:-1]|canonical else . end; # string representation def poly2s: "Polynomial(\(join(",")))"; # Polynomial division # Output [ quotient, remainder] def divrem($divisor):
($divisor|canonical) as$divisor
| { curr: canonical}
| .base = ((.curr|length) - ($divisor|length)) | until( .base < 0; (.curr[-1] /$divisor[-1]) as $res | .result += [$res]
| .curr |= .[0:-1]
|  reduce range (0;$divisor|length-1) as$i (.;
.curr[.base + $i] += (-$res * $divisor[$i])  )
| .base += -1
)
| [(.result | reverse),  (.curr | canonical)];

def demo($num;$den):
{$num,$den,
res: ($num | divrem($den)) }
| .quot = .res[0]
| .rem  = .res[1]
| del(.res)
| map_values(poly2s)
| "\(.num) / \(.den) = \(.quot) remainder \(.rem)";

demo( [-42, 0, -12, 1]; [-3, 1, 0, 0])
Output:
Polynomial(-42,0,-12,1) / Polynomial(-3,1,0,0) = Polynomial(-27,-9,1)
remainder Polynomial(-123)

## Julia

This task is straightforward with the help of Julia's Polynomials package.

using Polynomials

p = Poly([-42,0,-12,1])
q = Poly([-3,1])

d, r = divrem(p,q)

println(p, " divided by ", q, " is ", d, " with remainder ", r, ".")
Output:
-42 - 12x^2 + x^3 divided by -3 + x is -27.0 - 9.0x + x^2 with remainder -123.0.

## Kotlin

### Version 1

// version 1.1.51

typealias IAE = IllegalArgumentException

data class Solution(val quotient: DoubleArray, val remainder: DoubleArray)

fun polyDegree(p: DoubleArray): Int {
for (i in p.size - 1 downTo 0) {
if (p[i] != 0.0) return i
}
return Int.MIN_VALUE
}

fun polyShiftRight(p: DoubleArray, places: Int): DoubleArray {
if (places <= 0) return p
val pd = polyDegree(p)
if (pd + places >= p.size) {
throw IAE("The number of places to be shifted is too large")
}
val d = p.copyOf()
for (i in pd downTo 0) {
d[i + places] = d[i]
d[i] = 0.0
}
return d
}

fun polyMultiply(p: DoubleArray, m: Double) {
for (i in 0 until p.size) p[i] *= m
}

fun polySubtract(p: DoubleArray, s: DoubleArray) {
for (i in 0 until p.size) p[i] -= s[i]
}

fun polyLongDiv(n: DoubleArray, d: DoubleArray): Solution {
if (n.size != d.size) {
throw IAE("Numerator and denominator vectors must have the same size")
}
var nd = polyDegree(n)
val dd = polyDegree(d)
if (dd < 0) {
throw IAE("Divisor must have at least one one-zero coefficient")
}
if (nd < dd) {
throw IAE("The degree of the divisor cannot exceed that of the numerator")
}
val n2 = n.copyOf()
val q = DoubleArray(n.size)  // all elements zero by default
while (nd >= dd) {
val d2 = polyShiftRight(d, nd - dd)
q[nd - dd] = n2[nd] / d2[nd]
polyMultiply(d2, q[nd - dd])
polySubtract(n2, d2)
nd = polyDegree(n2)
}
return Solution(q, n2)
}

fun polyShow(p: DoubleArray) {
val pd = polyDegree(p)
for (i in pd downTo 0) {
val coeff = p[i]
if (coeff == 0.0) continue
print (when {
coeff ==  1.0  -> if (i < pd) " + " else ""
coeff == -1.0  -> if (i < pd) " - " else "-"
coeff <   0.0  -> if (i < pd) " - ${-coeff}" else "$coeff"
else           -> if (i < pd) " + $coeff" else "$coeff"
})
if (i > 1) print("x^$i") else if (i == 1) print("x") } println() } fun main(args: Array<String>) { val n = doubleArrayOf(-42.0, 0.0, -12.0, 1.0) val d = doubleArrayOf( -3.0, 1.0, 0.0, 0.0) print("Numerator : ") polyShow(n) print("Denominator : ") polyShow(d) println("-------------------------------------") val (q, r) = polyLongDiv(n, d) print("Quotient : ") polyShow(q) print("Remainder : ") polyShow(r) } Output: Output: Numerator : x^3 - 12.0x^2 - 42.0 Denominator : x - 3.0 ------------------------------------- Quotient : x^2 - 9.0x - 27.0 Remainder : -123.0 ### Version 2 More succinct version that provides an easy-to-use API. class Polynom(private vararg val factors: Double) { operator fun div(divisor: Polynom): Pair<Polynom, Polynom> { var curr = canonical().factors val right = divisor.canonical().factors val result = mutableListOf<Double>() for (base in curr.size - right.size downTo 0) { val res = curr.last() / right.last() result += res curr = curr.copyOfRange(0, curr.size - 1) for (i in 0 until right.size - 1) curr[base + i] -= res * right[i] } val quot = Polynom(*result.asReversed().toDoubleArray()) val rem = Polynom(*curr).canonical() return Pair(quot, rem) } private fun canonical(): Polynom { if (factors.last() != 0.0) return this for (newLen in factors.size downTo 1) if (factors[newLen - 1] != 0.0) return Polynom(*factors.copyOfRange(0, newLen)) return Polynom(factors[0]) } override fun toString() = "Polynom(${factors.joinToString(" ")})"
}

fun main() {
val num = Polynom(-42.0, 0.0, -12.0, 1.0)
val den = Polynom(-3.0, 1.0, 0.0, 0.0)

val (quot, rem) = num / den

print("$num /$den = $quot remainder$rem")
}
Output:
Polynom(-42.0 0.0 -12.0 1.0) / Polynom(-3.0 1.0 0.0 0.0) = Polynom(-27.0 -9.0 1.0) remainder Polynom(-123.0)

## Maple

As Maple is a symbolic computation system, polynomial arithmetic is, of course, provided by the language runtime. The remainder (rem) and quotient (quo) operations each allow for the other to be computed simultaneously by passing an unassigned name as an optional fourth argument. Since rem and quo deal also with multivariate polynomials, the indeterminate is passed as the third argument.

> p := randpoly( x ); # pick a random polynomial in x
5       4       3       2
p := -56 - 7 x  + 22 x  - 55 x  - 94 x  + 87 x

> rem( p, x^2 + 2, x, 'q' ); # remainder
220 + 169 x

> q; # quotient
3       2
-7 x  + 22 x  - 41 x - 138

> quo( p, x^2 + 2, x, 'r' ); # quotient
3       2
-7 x  + 22 x  - 41 x - 138

> r; # remainder
220 + 169 x
> expand( (x^2+2)*q + r - p ); # check
0

## Mathematica /Wolfram Language

PolynomialQuotientRemainder[x^3-12 x^2-42,x-3,x]

output:

{-27 - 9 x + x^2, -123}

## Nim

const MinusInfinity = -1

type
Polynomial = seq[int]
Term = tuple[coeff, exp: int]

func degree(p: Polynomial): int =
## Return the degree of a polynomial.
## "p" is supposed to be normalized.
result = if p.len > 0: p.len - 1 else: MinusInfinity

func normalize(p: var Polynomial) =
## Normalize a polynomial, removing useless zeroes.
while p[^1] == 0: discard p.pop()

func shr(p: Polynomial; n: int): Polynomial =
## Shift a polynomial of "n" positions to the right.
result.setLen(p.len + n)
result[n..^1] = p

func *=(p: var Polynomial; n: int) =
## Multiply in place a polynomial by an integer.
for item in p.mitems: item *= n
p.normalize()

func -=(a: var Polynomial; b: Polynomial) =
## Substract in place a polynomial from another polynomial.
for i, val in b: a[i] -= val
a.normalize()

func longdiv(a, b: Polynomial): tuple[q, r: Polynomial] =
## Compute the long division of a polynomial by another.
## Return the quotient and the remainder as polynomials.
result.r = a
if b.degree < 0: raise newException(DivByZeroDefect, "divisor cannot be zero.")
result.q.setLen(a.len)
while (let k = result.r.degree - b.degree; k >= 0):
var d = b shr k
result.q[k] = result.r[^1] div d[^1]
d *= result.q[k]
result.r -= d
result.q.normalize()

const Superscripts: array['0'..'9', string] = ["⁰", "¹", "²", "³", "⁴", "⁵", "⁶", "⁷", "⁸", "⁹"]

func superscript(n: Natural): string =
## Return the Unicode string to use to represent an exponent.
if n == 1:
return ""
for d in $n: result.add(Superscripts[d]) func $(term: Term): string =
## Return the string representation of a term.
if term.coeff == 0: "0"
elif term.exp == 0: $term.coeff else: let base = 'x' & superscript(term.exp) if term.coeff == 1: base elif term.coeff == -1: '-' & base else:$term.coeff & base

func $(poly: Polynomial): string = ## return the string representation of a polynomial. for idx in countdown(poly.high, 0): let coeff = poly[idx] var term: Term = (coeff: coeff, exp: idx) if result.len == 0: result.add$term
else:
if coeff > 0:
result.add $term elif coeff < 0: term.coeff = -term.coeff result.add '-' result.add$term

const
N = @[-42, 0, -12, 1]
D = @[-3, 1]

let (q, r) = longdiv(N, D)
echo "N = ", N
echo "D = ", D
echo "q = ", q
echo "r = ", r
Output:
N = x³-12x²-42
D = x-3
q = x²-9x-27
r = -123

## OCaml

First define some utility operations on polynomials as lists (with highest power coefficient first).

let rec shift n l = if n <= 0 then l else shift (pred n) (l @ [0.0])
let rec pad n l = if n <= 0 then l else pad (pred n) (0.0 :: l)
let rec norm = function | 0.0 :: tl -> norm tl | x -> x
let deg l = List.length (norm l) - 1

let zip op p q =
let d = (List.length p) - (List.length q) in

Then the main polynomial division function

let polydiv f g =
let rec aux f s q =
let ddif = (deg f) - (deg s) in
if ddif < 0 then (q, f) else
let k = (List.hd f) /. (List.hd s) in
let ks = List.map (( *.) k) (shift ddif s) in
let q' = zip (+.) q (shift ddif [k])
and f' = norm (List.tl (zip (-.) f ks)) in
aux f' s q' in
aux (norm f) (norm g) []

For output we need a pretty-printing function

let str_poly l =
let term v p = match (v, p) with
| (  _, 0) -> string_of_float v
| (1.0, 1) -> "x"
| (  _, 1) -> (string_of_float v) ^ "*x"
| (1.0, _) -> "x^" ^ (string_of_int p)
| _ -> (string_of_float v) ^ "*x^" ^ (string_of_int p) in
let rec terms = function
| [] -> []
| h :: t ->
if h = 0.0 then (terms t) else (term h (List.length t)) :: (terms t) in
String.concat " + " (terms l)

and then the example

let _ =
let f = [1.0; -4.0; 6.0; 5.0; 3.0] and g = [1.0; 2.0; 1.0] in
let q, r = polydiv f g in
Printf.printf
" (%s) div (%s)\ngives\nquotient:\t(%s)\nremainder:\t(%s)\n"
(str_poly f) (str_poly g) (str_poly q) (str_poly r)

gives the output:

(x^4 + -4.*x^3 + 6.*x^2 + 5.*x + 3.) div (x^2 + 2.*x + 1.)
gives
quotient:	(x^2 + -6.*x + 17.)
remainder:	(-23.*x + -14.)

## Octave

Octave has already facilities to divide two polynomials (deconv(n,d)); and the reason to adopt the convention of keeping the highest power coefficient first, is to make the code compatible with builtin functions: we can use polyout to output the result.

function [q, r] = poly_long_div(n, d)
gd = length(d);
pv = zeros(1, length(n));
pv(1:gd) = d;
if ( length(n) >= gd )
q = [];
while ( length(n) >= gd )
q = [q, n(1)/pv(1)];
n = n - pv .* (n(1)/pv(1));
n = shift(n, -1);           %
tn = n(1:length(n)-1);      % eat the higher power term
n = tn;                     %
tp = pv(1:length(pv)-1);
pv = tp;                    % make pv the same length of n
endwhile
r = n;
else
q = [0];
r = n;
endif
endfunction

[q, r] = poly_long_div([1,-12,0,-42], [1,-3]);
polyout(q, 'x');
polyout(r, 'x');
disp("");
[q, r] = poly_long_div([1,-12,0,-42], [1,1,-3]);
polyout(q, 'x');
polyout(r, 'x');
disp("");
[q, r] = poly_long_div([1,3,2], [1,1]);
polyout(q, 'x');
polyout(r, 'x');
disp("");
[q, r] = poly_long_div([1,3], [1,-12,0,-42]);
polyout(q, 'x');
polyout(r, 'x');

## PARI/GP

This uses the built-in PARI polynomials.

poldiv(a,b)={
my(rem=a%b);
[(a - rem)/b, rem]
};
poldiv(x^9+1, x^3+x-3)

Alternately, use the built-in function divrem:

divrem(x^9+1, x^3+x-3)~

## Perl

This solution keeps the highest power coefficient first, like OCaml solution and Octave solution.

Translation of: Octave
use strict;
use List::Util qw(min);

sub poly_long_div
{
my ($rn,$rd) = @_;

my @n = @$rn; my$gd = scalar(@$rd); if ( scalar(@n) >=$gd ) {
my @q = ();
while ( scalar(@n) >= $gd ) { my$piv = $n[0]/$rd->[0];
push @q, $piv;$n[$_] -=$rd->[$_] *$piv foreach ( 0 .. min(scalar(@n), $gd)-1 ); shift @n; } return ( \@q, \@n ); } else { return ( [0],$rn );
}
}
sub poly_print
{
my @c = @_;
my $l = scalar(@c); for(my$i=0; $i <$l; $i++) { print$c[$i]; print "x^" . ($l-$i-1) . " + " if ($i < ($l-1)); } print "\n"; } my ($q, $r); ($q, $r) = poly_long_div([1, -12, 0, -42], [1, -3]); poly_print(@$q);
poly_print(@$r); print "\n"; ($q, $r) = poly_long_div([1,-12,0,-42], [1,1,-3]); poly_print(@$q);
poly_print(@$r); print "\n"; ($q, $r) = poly_long_div([1,3,2], [1,1]); poly_print(@$q);
poly_print(@$r); print "\n"; # the example from the OCaml solution ($q, $r) = poly_long_div([1,-4,6,5,3], [1,2,1]); poly_print(@$q);
print.polynomial(r$r) ## Racket #lang racket (define (deg p) (for/fold ([d -inf.0]) ([(pi i) (in-indexed p)]) (if (zero? pi) d i))) (define (lead p) (vector-ref p (deg p))) (define (mono c d) (build-vector (+ d 1) (λ(i) (if (= i d) c 0)))) (define (poly*cx^n c n p) (vector-append (make-vector n 0) (for/vector ([pi p]) (* c pi)))) (define (poly+ p q) (poly/lin 1 p 1 q)) (define (poly- p q) (poly/lin 1 p -1 q)) (define (poly/lin a p b q) (cond [(< (deg p) 0) q] [(< (deg q) 0) p] [(< (deg p) (deg q)) (poly/lin b q a p)] [else (define ap+bq (for/vector #:length (+ (deg p) 1) #:fill 0 ([pi p] [qi q]) (+ (* a pi) (* b qi)))) (for ([i (in-range (+ (deg q) 1) (+ (deg p) 1))]) (vector-set! ap+bq i (* a (vector-ref p i)))) ap+bq])) (define (poly/ n d) (define N (deg n)) (define D (deg d)) (cond [(< N 0) (error 'poly/ "can't divide by zero")] [(< N D) (values 0 n)] [else (define c (/ (lead n) (lead d))) (define q (mono c (- N D))) (define r (poly- n (poly*cx^n c (- N D) d))) (define-values (q1 r1) (poly/ r d)) (values (poly+ q q1) r1)])) ; Example: (poly/ #(-42 0 -12 1) #(-3 1)) ; Output: '#(-27 -9 1) '#(-123 0) ## Raku (formerly Perl 6) Works with: rakudo version 2018.10 Translation of: Perl for the core algorithm; original code for LaTeX pretty-printing. sub poly_long_div ( @n is copy, @d ) { return [0], |@n if +@n < +@d; my @q = gather while +@n >= +@d { @n = @n Z- flat ( ( @d X* take ( @n[0] / @d[0] ) ), 0 xx * ); @n.shift; } return @q, @n; } sub xP ($power ) { $power>1 ?? "x^$power" !! $power==1 ?? 'x' !! '' } sub poly_print ( @c ) { join ' + ', @c.kv.map: {$^v ~ xP( @c.end - $^k ) } } my @polys = [ [ 1, -12, 0, -42 ], [ 1, -3 ] ], [ [ 1, -12, 0, -42 ], [ 1, 1, -3 ] ], [ [ 1, 3, 2 ], [ 1, 1 ] ], [ [ 1, -4, 6, 5, 3 ], [ 1, 2, 1 ] ]; say '$\begin{array}{rr}'; for @polys -> [ @a, @b ] { printf Q"%s , & %s \\\\\n", poly_long_div( @a, @b ).map: { poly_print(_) }; } say '\end{array}$'; Output: ${\displaystyle {\begin{array}{rr}1x^{2}+-9x+-27,&-123\\1x+-13,&16x+-81\\1x+2,&0\\1x^{2}+-6x+17,&-23x+-14\\\end{array}}}$ ## REXX /* REXX needed by some... */ z='1 -12 0 -42' /* Numerator */ n='1 -3' /* Denominator */ zx=z nx=n copies('0 ',words(z)-words(n)) qx='' /* Quotient */ Do Until words(zx)<words(n) Parse Value div(zx,nx) With q zx qx=qx q nx=subword(nx,1,words(nx)-1) End Say '('show(z)')/('show(n)')=('show(qx)')' Say 'Remainder:' show(zx) Exit div: Procedure Parse Arg z,n q=word(z,1)/word(n,1) zz='' Do i=1 To words(z) zz=zz word(z,i)-q*word(n,i) End Return q subword(zz,2) show: Procedure Parse Arg poly d=words(poly)-1 res='' Do i=1 To words(poly) Select When d>1 Then fact='*x**'d When d=1 Then fact='*x' Otherwise fact='' End Select When word(poly,i)=0 Then p='' When word(poly,i)=1 Then p='+'substr(fact,2) When word(poly,i)=-1 Then p='-'substr(fact,2) When word(poly,i)<0 Then p=word(poly,i)||fact Otherwise p='+'word(poly,i)||fact End res=res p d=d-1 End Return strip(space(res,0),'L','+') Output: (x**3-12*x**2-42)/(x-3)=(x**2-9*x-27) Remainder: -123 ## RPL Works with: HP version 49 '-42-12*X^2+X^3' 'X-3' DIV2 Output: 2: 'X^2-9*X-27' 1: -123 ## Ruby Implementing the algorithm given in the task description: def polynomial_long_division(numerator, denominator) dd = degree(denominator) raise ArgumentError, "denominator is zero" if dd < 0 if dd == 0 return [multiply(numerator, 1.0/denominator[0]), [0]*numerator.length] end q = [0] * numerator.length while (dn = degree(numerator)) >= dd d = shift_right(denominator, dn - dd) q[dn-dd] = numerator[dn] / d[degree(d)] d = multiply(d, q[dn-dd]) numerator = subtract(numerator, d) end [q, numerator] end def degree(ary) idx = ary.rindex(&:nonzero?) idx ? idx : -1 end def shift_right(ary, n) [0]*n + ary[0, ary.length - n] end def subtract(a1, a2) a1.zip(a2).collect {|v1,v2| v1 - v2} end def multiply(ary, num) ary.collect {|x| x * num} end f = [-42, 0, -12, 1] g = [-3, 1, 0, 0] q, r = polynomial_long_division(f, g) puts "#{f} / #{g} => #{q} remainder #{r}" # => [-42, 0, -12, 1] / [-3, 1, 0, 0] => [-27, -9, 1, 0] remainder [-123, 0, 0, 0] g = [-3, 1, 1, 0] q, r = polynomial_long_division(f, g) puts "#{f} / #{g} => #{q} remainder #{r}" # => [-42, 0, -12, 1] / [-3, 1, 1, 0] => [-13, 1, 0, 0] remainder [-81, 16, 0, 0] Implementing the algorithms on the wikipedia page -- uglier code but nicer user interface def polynomial_division(f, g) if g.length == 0 or (g.length == 1 and g[0] == 0) raise ArgumentError, "denominator is zero" elsif g.length == 1 [f.collect {|x| Float(x)/g[0]}, [0]] elsif g.length == 2 synthetic_division(f, g) else higher_degree_synthetic_division(f, g) end end def synthetic_division(f, g) board = [f] << Array.new(f.length) << Array.new(f.length) board[2][0] = board[0][0] 1.upto(f.length - 1).each do |i| board[1][i] = board[2][i-1] * -g[1] board[2][i] = board[0][i] + board[1][i] end [board[2][0..-2], [board[2][-1]]] end # an ugly mess of array index arithmetic # http://en.wikipedia.org/wiki/Polynomial_long_division#Higher_degree_synthetic_division def higher_degree_synthetic_division(f, g) # [use] the negative coefficients of the denominator following the leading term lhs = g[1..-1].collect {|x| -x} board = [f] q = [] 1.upto(f.length - lhs.length).each do |i| n = 2*i - 1 # underline the leading coefficient of the right-hand side, multiply it by # the left-hand coefficients and write the products beneath the next columns # on the right. q << board[n-1][i-1] board << Array.new(f.length).fill(0, i) # row n (lhs.length).times do |j| board[n][i+j] = q[-1]*lhs[j] end # perform an addition board << Array.new(f.length).fill(0, i) # row n+1 (lhs.length + 1).times do |j| board[n+1][i+j] = board[n-1][i+j] + board[n][i+j] if i+j < f.length end end # the remaining numbers in the bottom row correspond to the coefficients of the remainder r = board[-1].compact q = [0] if q.empty? [q, r] end f = [1, -12, 0, -42] g = [1, -3] q, r = polynomial_division(f, g) puts "#{f} / #{g} => #{q} remainder #{r}" # => [1, -12, 0, -42] / [1, -3] => [1, -9, -27] remainder [-123] g = [1, 1, -3] q, r = polynomial_division(f, g) puts "#{f} / #{g} => #{q} remainder #{r}" # => [1, -12, 0, -42] / [1, 1, -3] => [1, -13] remainder [16, -81] Best of both worlds: Translation of: Tcl def polynomial_division(f, g) if g.length == 0 or (g.length == 1 and g[0] == 0) raise ArgumentError, "denominator is zero" end return [[0], f] if f.length < g.length q, n = [], f.dup while n.length >= g.length q << Float(n[0]) / g[0] n[0, g.length].zip(g).each_with_index do |pair, i| n[i] = pair[0] - q[-1] * pair[1] end n.shift end q = [0] if q.empty? n = [0] if n.empty? [q, n] end f = [1, -12, 0, -42] g = [1, -3] q, r = polynomial_division(f, g) puts "#{f} / #{g} => #{q} remainder #{r}" # => [1, -12, 0, -42] / [1, -3] => [1.0, -9.0, -27.0] remainder [-123.0] g = [1, 1, -3] q, r = polynomial_division(f, g) puts "#{f} / #{g} => #{q} remainder #{r}" # => [1, -12, 0, -42] / [1, 1, -3] => [1.0, -13.0] remainder [16.0, -81.0] ## Sidef Translation of: Perl func poly_long_div(rn, rd) { var n = rn.map{_} var gd = rd.len if (n.len >= gd) { return(gather { while (n.len >= gd) { var piv = n[0]/rd[0] take(piv) { |i| n[i] -= (rd[i] * piv) } << ^(n.len min gd) n.shift } }, n) } return([0], rn) } Example: func poly_print(c) { var l = c.len c.each_kv {|i, n| print n print("x^", (l - i - 1), " + ") if (i < l-1) } print "\n"; } var poly = [ Pair([1,-12,0,-42], [1, -3]), Pair([1,-12,0,-42], [1,1,-3]), Pair( [1,3,2], [1,1]), Pair( [1,-4,6,5,3], [1,2,1]), ] poly.each { |pair| var (q, r) = poly_long_div(pair.first, pair.second) poly_print(q) poly_print(r) print "\n" } Output: 1x^2 + -9x^1 + -27 -123 1x^1 + -13 16x^1 + -81 1x^1 + 2 0 1x^2 + -6x^1 + 17 -23x^1 + -14 ## Slate define: #Polynomial &parents: {Comparable} &slots: {#coefficients -> ExtensibleArray new}. p@(Polynomial traits) new &capacity: n [ p cloneSettingSlots: #(coefficients) to: {p coefficients new &capacity: n} ]. p@(Polynomial traits) newFrom: seq@(Sequence traits) [ p clone >> [coefficients: (seq as: p coefficients). normalize. ] ]. p@(Polynomial traits) copy [ p cloneSettingSlots: #(coefficients) to: {p coefficients copy} ]. p1@(Polynomial traits) >= p2@(Polynomial traits) [p1 degree >= p2 degree]. p@(Polynomial traits) degree [p coefficients indexOfLastSatisfying: [| :n | n isZero not]]. p@(Polynomial traits) normalize [ [p degree isPositive /\ [p coefficients last isZero]] whileTrue: [p coefficients removeLast] ]. p@(Polynomial traits) * n@(Number traits) [ p newFrom: (p coefficients collect: [| :x | x * n]) ]. p@(Polynomial traits) / n@(Number traits) [ p newFrom: (p coefficients collect: [| :x | x / n]) ]. p1@(Polynomial traits) minusCoefficients: p2@(Polynomial traits) [ p1 newFrom: (p1 coefficients with: p2 coefficients collect: #- er) ]. p@(Polynomial traits) / denom@(Polynomial traits) [ p >= denom ifTrue: [| n q | n: p copy. q: p new. [n >= denom] whileTrue: [| piv | piv: p coefficients last / denom coefficients last. q coefficients add: piv. n: (n minusCoefficients: denom * piv). n normalize]. n coefficients isEmpty ifTrue: [n coefficients add: 0]. {q. n}] ifFalse: [{p newFrom: #(0). p copy}] ]. ## Smalltalk Works with: GNU Smalltalk Object subclass: Polynomial [ |coeffs| Polynomial class >> new [ ^ super basicNew init ] init [ coeffs := OrderedCollection new. ^ self ] Polynomial class >> newWithCoefficients: coefficients [ |r| r := super basicNew. ^ r initWithCoefficients: coefficients ] initWithCoefficients: coefficients [ coeffs := coefficients asOrderedCollection. ^ self ] / denominator [ |n q| n := self deepCopy. self >= denominator ifTrue: [ q := Polynomial new. [ n >= denominator ] whileTrue: [ |piv| piv := (n coeff: 0) / (denominator coeff: 0). q addCoefficient: piv. n := n - (denominator * piv). n clean ]. ^ { q . (n degree) > 0 ifTrue: [ n ] ifFalse: [ n addCoefficient: 0. n ] } ] ifFalse: [ ^ { Polynomial newWithCoefficients: #( 0 ) . self deepCopy } ] ] * constant [ |r| r := self deepCopy. 1 to: (coeffs size) do: [ :i | r at: i put: ((r at: i) * constant) ]. ^ r ] at: index [ ^ coeffs at: index ] at: index put: obj [ ^ coeffs at: index put: obj ] >= anotherPoly [ ^ (self degree) >= (anotherPoly degree) ] degree [ ^ coeffs size ] - anotherPoly [ "This is not a real subtraction between Polynomial: it is an internal method ..." |a| a := self deepCopy. 1 to: ( (coeffs size) min: (anotherPoly degree) ) do: [ :i | a at: i put: ( (a at: i) - (anotherPoly at: i) ) ]. ^ a ] coeff: index [ ^ coeffs at: (index + 1) ] addCoefficient: coeff [ coeffs add: coeff ] clean [ [ (coeffs size) > 0 ifTrue: [ (coeffs at: 1) = 0 ] ifFalse: [ false ] ] whileTrue: [ coeffs removeFirst ]. ] display [ 1 to: (coeffs size) do: [ :i | (coeffs at: i) display. i < (coeffs size) ifTrue: [ ('x^%1 + ' % {(coeffs size) - i} ) display ] ] ] displayNl [ self display. Character nl display ] ]. |res| res := OrderedCollection new. res add: ((Polynomial newWithCoefficients: #( 1 -12 0 -42) ) / (Polynomial newWithCoefficients: #( 1 -3 ) )) ; add: ((Polynomial newWithCoefficients: #( 1 -12 0 -42) ) / (Polynomial newWithCoefficients: #( 1 1 -3 ) )). res do: [ :o | (o at: 1) display. ' with rest: ' display. (o at: 2) displayNl ] ## SPAD Works with: FriCAS Works with: OpenAxiom Works with: Axiom (1) -> monicDivide(x^3-12*x^2-42,x-3,'x) 2 (1) [quotient = x - 9x - 27,remainder = - 123] Type: Record(quotient: Polynomial(Integer),remainder: Polynomial(Integer)) Domain:[1] ## Swift Translation of: Kotlin protocol Dividable { static func / (lhs: Self, rhs: Self) -> Self } extension Int: Dividable { } struct Solution<T> { var quotient: [T] var remainder: [T] } func polyDegree<T: SignedNumeric>(_ p: [T]) -> Int { for i in stride(from: p.count - 1, through: 0, by: -1) where p[i] != 0 { return i } return Int.min } func polyShiftRight<T: SignedNumeric>(p: [T], places: Int) -> [T] { guard places > 0 else { return p } let deg = polyDegree(p) assert(deg + places < p.count, "Number of places to shift too large") var res = p for i in stride(from: deg, through: 0, by: -1) { res[i + places] = res[i] res[i] = 0 } return res } func polyMul<T: SignedNumeric>(_ p: inout [T], by: T) { for i in 0..<p.count { p[i] *= by } } func polySub<T: SignedNumeric>(_ p: inout [T], by: [T]) { for i in 0..<p.count { p[i] -= by[i] } } func polyLongDiv<T: SignedNumeric & Dividable>(numerator n: [T], denominator d: [T]) -> Solution<T>? { guard n.count == d.count else { return nil } var nDeg = polyDegree(n) let dDeg = polyDegree(d) guard dDeg >= 0, nDeg >= dDeg else { return nil } var n2 = n var quo = [T](repeating: 0, count: n.count) while nDeg >= dDeg { let i = nDeg - dDeg var d2 = polyShiftRight(p: d, places: i) quo[i] = n2[nDeg] / d2[nDeg] polyMul(&d2, by: quo[i]) polySub(&n2, by: d2) nDeg = polyDegree(n2) } return Solution(quotient: quo, remainder: n2) } func polyPrint<T: SignedNumeric & Comparable>(_ p: [T]) { let deg = polyDegree(p) for i in stride(from: deg, through: 0, by: -1) where p[i] != 0 { let coeff = p[i] switch coeff { case 1 where i < deg: print(" + ", terminator: "") case 1: print("", terminator: "") case -1 where i < deg: print(" - ", terminator: "") case -1: print("-", terminator: "") case _ where coeff < 0 && i < deg: print(" - \(-coeff)", terminator: "") case _ where i < deg: print(" + \(coeff)", terminator: "") case _: print("\(coeff)", terminator: "") } if i > 1 { print("x^\(i)", terminator: "") } else if i == 1 { print("x", terminator: "") } } print() } let n = [-42, 0, -12, 1] let d = [-3, 1, 0, 0] print("Numerator: ", terminator: "") polyPrint(n) print("Denominator: ", terminator: "") polyPrint(d) guard let sol = polyLongDiv(numerator: n, denominator: d) else { fatalError() } print("----------") print("Quotient: ", terminator: "") polyPrint(sol.quotient) print("Remainder: ", terminator: "") polyPrint(sol.remainder) Output: Numerator: x^3 - 12x^2 - 42 Denominator: x - 3 ---------- Quotient: x^2 - 9x - 27 Remainder: -123 ## Tcl Works with: Tcl version 8.5 and later # poldiv - Divide two polynomials n and d. # Result is a list of two polynomials, q and r, where n = qd + r # and the degree of r is less than the degree of b. # Polynomials are represented as lists, where element 0 is the # x**0 coefficient, element 1 is the x**1 coefficient, and so on. proc poldiv {a b} { # Toss out leading zero coefficients efficiently while {[lindex$a end] == 0} {set a [lrange $a[set a {}] 0 end-1]} while {[lindex$b end] == 0} {set b [lrange $b[set b {}] 0 end-1]} if {[llength$a] < [llength $b]} { return [list 0$a]
}

# Rearrange the terms to put highest powers first
set n [lreverse $a] set d [lreverse$b]

# Carry out classical long division, accumulating quotient coefficients
# in q, and replacing n with the remainder.
set q {}
while {[llength $n] >= [llength$d]} {
set qd [expr {[lindex $n 0] / [lindex$d 0]}]
set i 0
foreach nd [lrange $n 0 [expr {[llength$d] - 1}]] dd $d { lset n$i [expr {$nd -$qd * $dd}] incr i } lappend q$qd
set n [lrange $n 1 end] } # Return quotient and remainder, constant term first return [list [lreverse$q] [lreverse $n]] } # Demonstration lassign [poldiv {-42. 0. -12. 1.} {-3. 1. 0. 0.}] Q R puts [list Q =$Q]
puts [list R = $R] ## Ursala The input is a pair of lists of coefficients in order of increasing degree. Trailing zeros can be omitted. The output is a pair of lists (q,r), the quotient and remainder polynomial coefficients. This is a straightforward implementation of the algorithm in terms of list operations (fold, zip, map, distribute, etc.) instead of array indexing, hence not unnecessarily verbose. #import std #import flo polydiv = zeroid~-l~~; leql?rlX\~&NlX ^H\(@rNrNSPXlHDlS |\ :/0.) @NlX //=> ?( @lrrPX ==!| zipp0.; @x not zeroid+ ==@h->hr ~&t, (^lryPX/~&lrrl2C minus^*p/~&rrr times*lrlPD)^/div@bzPrrPlXO ~&, @r ^|\~& ~&i&& :/0.) test program: #cast %eLW example = polydiv(<-42.,0.,-12.,1.>,<-3.,1.,0.,0.>) output: ( <-2.700000e+01,-9.000000e+00,1.000000e+00>, <-1.230000e+02>) ## VBA Translation of: Phix Option Base 1 Function degree(p As Variant) For i = UBound(p) To 1 Step -1 If p(i) <> 0 Then degree = i Exit Function End If Next i degree = -1 End Function Function poly_div(ByVal n As Variant, ByVal d As Variant) As Variant If UBound(d) < UBound(n) Then ReDim Preserve d(UBound(n)) End If Dim dn As Integer: dn = degree(n) Dim dd As Integer: dd = degree(d) If dd < 0 Then poly_div = CVErr(xlErrDiv0) Exit Function End If Dim quot() As Integer ReDim quot(dn) Do While dn >= dd Dim k As Integer: k = dn - dd Dim qk As Integer: qk = n(dn) / d(dd) quot(k + 1) = qk Dim d2() As Variant d2 = d ReDim Preserve d2(UBound(d) - k) For i = 1 To UBound(d2) n(UBound(n) + 1 - i) = n(UBound(n) + 1 - i) - d2(UBound(d2) + 1 - i) * qk Next i dn = degree(n) Loop poly_div = Array(quot, n) '-- (n is now the remainder) End Function Function poly(si As Variant) As String '-- display helper Dim r As String For t = UBound(si) To 1 Step -1 Dim sit As Integer: sit = si(t) If sit <> 0 Then If sit = 1 And t > 1 Then r = r & IIf(r = "", "", " + ") Else If sit = -1 And t > 1 Then r = r & IIf(r = "", "-", " - ") Else If r <> "" Then r = r & IIf(sit < 0, " - ", " + ") sit = Abs(sit) End If r = r & CStr(sit) End If End If r = r & IIf(t > 1, "x" & IIf(t > 2, t - 1, ""), "") End If Next t If r = "" Then r = "0" poly = r End Function Function polyn(s As Variant) As String Dim t() As String ReDim t(2 * UBound(s)) For i = 1 To 2 * UBound(s) Step 2 t(i) = poly(s((i + 1) / 2)) Next i t(1) = String$(45 - Len(t(1)) - Len(t(3)), " ") & t(1)
t(2) = "/"
t(4) = "="
t(6) = "rem"
polyn = Join(t, " ")
End Function

Public Sub main()
Dim tests(7) As Variant
tests(1) = Array(Array(-42, 0, -12, 1), Array(-3, 1))
tests(2) = Array(Array(-3, 1), Array(-42, 0, -12, 1))
tests(3) = Array(Array(-42, 0, -12, 1), Array(-3, 1, 1))
tests(4) = Array(Array(2, 3, 1), Array(1, 1))
tests(5) = Array(Array(3, 5, 6, -4, 1), Array(1, 2, 1))
tests(6) = Array(Array(3, 0, 7, 0, 0, 0, 0, 0, 3, 0, 0, 1), Array(1, 0, 0, 5, 0, 0, 0, 1))
tests(7) = Array(Array(-56, 87, -94, -55, 22, -7), Array(2, 0, 1))
Dim num As Variant, denom As Variant, quot As Variant, rmdr As Variant
For i = 1 To 7
num = tests(i)(1)
denom = tests(i)(2)
tmp = poly_div(num, denom)
quot = tmp(1)
rmdr = tmp(2)
Debug.Print polyn(Array(num, denom, quot, rmdr))
Next i
End Sub
Output:
x3 - 12x2 - 42 / x - 3 = x2 - 9x - 27 rem -123
x - 3 / x3 - 12x2 - 42 = 0 rem x - 3
x3 - 12x2 - 42 / x2 + x - 3 = x - 13 rem 16x - 81
x2 + 3x + 2 / x + 1 = x + 2 rem 0
x4 - 4x3 + 6x2 + 5x + 3 / x2 + 2x + 1 = x2 - 6x + 17 rem -23x - 14
x11 + 3x8 + 7x2 + 3 / x7 + 5x3 + 1 = x4 + 3x - 5 rem -16x4 + 25x3 + 7x2 - 3x + 8
-7x5 + 22x4 - 55x3 - 94x2 + 87x - 56 / x2 + 2 = -7x3 + 22x2 - 41x - 138 rem 169x + 220

## Wren

Translation of: Kotlin

### Version 1

Library: Wren-dynamic
import "./dynamic" for Tuple

var Solution = Tuple.create("Solution", ["quotient", "remainder"])

var polyDegree = Fn.new { |p|
for (i in p.count-1..0) if (p[i] != 0) return i
return -2.pow(31)
}

var polyShiftRight = Fn.new { |p, places|
if (places <= 0) return p
var pd = polyDegree.call(p)
if (pd + places >= p.count) {
Fiber.abort("The number of places to be shifted is too large.")
}
var d = p.toList
for (i in pd..0) {
d[i + places] = d[i]
d[i] = 0
}
return d
}

var polyMultiply = Fn.new { |p, m|
for (i in 0...p.count) p[i] = p[i] * m
}

var polySubtract = Fn.new { |p, s|
for (i in 0...p.count) p[i] = p[i] - s[i]
}

var polyLongDiv = Fn.new { |n, d|
if (n.count != d.count) {
Fiber.abort("Numerator and denominator vectors must have the same size")
}
var nd = polyDegree.call(n)
var dd = polyDegree.call(d)
if (dd < 0) {
Fiber.abort("Divisor must have at least one one-zero coefficient")
}
if (nd < dd) {
Fiber.abort("The degree of the divisor cannot exceed that of the numerator")
}
var n2 = n.toList
var q = List.filled(n.count, 0)
while (nd >= dd) {
var d2 = polyShiftRight.call(d, nd - dd)
q[nd - dd] = n2[nd] / d2[nd]
polyMultiply.call(d2, q[nd - dd])
polySubtract.call(n2, d2)
nd = polyDegree.call(n2)
}
return Solution.new(q, n2)
}

var polyShow = Fn.new { |p|
var pd = polyDegree.call(p)
for (i in pd..0) {
var coeff = p[i]
if (coeff != 0) {
System.write(
(coeff ==  1) ? ((i < pd) ? " + " :  "") :
(coeff == -1) ? ((i < pd) ? " - " : "-") :
(coeff <   0) ? ((i < pd) ? " - %(-coeff)" : "%(coeff)") :
((i < pd) ? " + %( coeff)" : "%(coeff)")
)
if (i > 1) {
System.write("x^%(i)")
} else if (i == 1) {
System.write("x")
}
}
}
System.print()
}

var n = [-42, 0, -12, 1]
var d = [ -3, 1,   0, 0]
System.write("Numerator   : ")
polyShow.call(n)
System.write("Denominator : ")
polyShow.call(d)
System.print("-------------------------------------")
var sol = polyLongDiv.call(n, d)
System.write("Quotient    : ")
polyShow.call(sol.quotient)
System.write("Remainder   : ")
polyShow.call(sol.remainder)
Output:
Numerator   : x^3 - 12x^2 - 42
Denominator : x - 3
-------------------------------------
Quotient    : x^2 - 9x - 27
Remainder   : -123

### Version 2

class Polynom {
construct new(factors) {
_factors = factors.toList
}

factors { _factors.toList }

/(divisor) {
var curr = canonical().factors
var right = divisor.canonical().factors
var result = []
var base = curr.count - right.count
while (base >= 0) {
var res = curr[-1] / right[-1]
curr = curr[0...-1]
for (i in 0...right.count-1) {
curr[base + i] = curr[base + i] - res * right[i]
}
base = base - 1
}
var quot = Polynom.new(result[-1..0])
var rem = Polynom.new(curr).canonical()
return [quot, rem]
}

canonical() {
if (_factors[-1] != 0) return this
var newLen = factors.count
while (newLen > 0) {
if (_factors[newLen-1] != 0) return Polynom.new(_factors[0...newLen])
newLen = newLen - 1
}
return Polynom.new(_factors[0..0])
}

toString { "Polynomial(%(_factors.join(", ")))" }
}

var num = Polynom.new([-42, 0, -12, 1])
var den = Polynom.new([-3, 1, 0, 0])
var res = num / den
var quot = res[0]
var rem = res[1]
System.print("%(num) / %(den) = %(quot) remainder %(rem)")
Output:
Polynomial(-42, 0, -12, 1) / Polynomial(-3, 1, 0, 0) = Polynomial(-27, -9, 1) remainder Polynomial(-123)

## zkl

fcn polyLongDivision(a,b){  // (a0 + a1x + a2x^2 + a3x^3 ...)
_assert_(degree(b)>=0,"degree(%s) < 0".fmt(b));
q:=List.createLong(a.len(),0.0);
q[z]=m;
d,a = d.apply('*(m)), a.zipWith('-,d);
}
return(q,a);		// may have trailing zero elements
}
fcn degree(v){  // -1,0,..len(v)-1, -1 if v==0
v.len() - v.copy().reverse().filter1n('!=(0)) - 1;
}
fcn polyString(terms){ // (a0,a1,a2...)-->"a0 + a1x + a2x^2 ..."
str:=[0..].zipWith('wrap(n,a){ if(a) "+ %sx^%s ".fmt(a,n) else "" },terms)
.pump(String)
.replace("x^0 "," ").replace(" 1x"," x").replace("x^1 ","x ")
.replace("+ -", "- ");
if(not str)     return(" ");  // all zeros
if(str[0]=="+") str[1,*];     // leave leading space
else            String("-",str[2,*]);
}
q,r:=polyLongDivision(T(-42.0, 0.0, -12.0, 1.0),T(-3.0, 1.0));
println("Quotient  = ",polyString(q));
println("Remainder = ",polyString(r));
Output:
Quotient  = -27 - 9x + x^2
Remainder = -123