Polynomial long division: Difference between revisions

=={{header|Octave}}==

Octave has already facilities to divide two polynomials; and the reason to adopt the convention of keeping the higher power coefficient first, is to make the code compatible with builtin functions: we can use <tt>polyout</tt> to output the result.

<lang octave>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');</lang>