Special neighbor primes: Difference between revisions
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=={{header|ALGOL 68}}==
{{libheader|ALGOL 68-primes}}
Very similar to [[Neighbour_primes#ALGOL_68|The ALGOL 68 sample in the Neighbour primes task]]
<syntaxhighlight lang="algol68">BEGIN # find adjacent primes p1, p2 such that p1 + p2 - 1 is also prime #
PR read "primes.incl.a68" PR
Line 128 ⟶ 129:
( 73 + 79 ) - 1 = 151
</pre>
=={{header|Arturo}}==
<syntaxhighlight lang="arturo">primesBelow100: select 1..100 => prime?
loop 1..dec size primesBelow100 'p [
p1: primesBelow100\[p-1]
p2: primesBelow100\[p]
if prime? dec p1 + p2 ->
print ["(" p1 "," p2 ")"]
]</syntaxhighlight>
{{out}}
<pre>( 3 , 5 )
( 5 , 7 )
( 7 , 11 )
( 11 , 13 )
( 13 , 17 )
( 19 , 23 )
( 29 , 31 )
( 31 , 37 )
( 41 , 43 )
( 43 , 47 )
( 61 , 67 )
( 67 , 71 )
( 73 , 79 )</pre>
=={{header|AWK}}==
Line 177 ⟶ 204:
73,79 -> 151
Special neighbor primes 3-99: 13
</pre>
=={{header|BASIC}}==
==={{header|FreeBASIC}}===
<syntaxhighlight lang="freebasic">#include"isprime.bas"
function nextprime( n as uinteger ) as uinteger
'finds the next prime after n
if n = 0 then return 2
if n < 3 then return n + 1
dim as integer q = n + 2
while not isprime(q)
q+=2
wend
return q
end function
dim as uinteger p1, p2
for p1 = 3 to 100 step 2
p2 = nextprime(p1)
if isprime(p1) andalso p2<100 andalso isprime( p1 + p2 - 1 ) then
print p1, p2, p1 + p2 - 1
end if
next p1
</syntaxhighlight>
{{out}}<pre>
3 5 7
5 7 11
7 11 17
11 13 23
13 17 29
19 23 41
29 31 59
31 37 67
41 43 83
43 47 89
61 67 127
67 71 137
73 79 151
</pre>
==={{header|GW-BASIC}}===
{{works with|BASICA}}
<syntaxhighlight lang="gwbasic">10 FOR P = 3 TO 99 STEP 2
20 GOSUB 130
30 IF Q = 0 THEN GOTO 110
40 GOSUB 220
50 IF P2>100 THEN END
60 T = P
70 P = P2 + T - 1
80 GOSUB 130
90 IF Q = 1 THEN PRINT USING "## + ## - 1 = ###";T;P2;P
100 P=T
110 NEXT P
120 END
130 REM tests if a number is prime
140 Q=0
150 IF P=3 THEN Q=1:RETURN
160 I=1
170 I=I+1
180 IF INT(P/I)*I = P THEN RETURN
190 IF I*I<=P THEN GOTO 170
200 Q = 1
210 RETURN
220 REM finds the next prime after P, result in P2
230 IF P = 0 THEN P2 = 2: RETURN
240 IF P<3 THEN P2 = P + 1: RETURN
250 T = P
260 P = P + 1
270 GOSUB 130
280 IF Q = 1 THEN P2 = P: P = T: RETURN
290 GOTO 260</syntaxhighlight>
{{out}}
<pre> 3 + 5 - 1 = 7
5 + 7 - 1 = 11
7 + 11 - 1 = 17
11 + 13 - 1 = 23
13 + 17 - 1 = 29
19 + 23 - 1 = 41
29 + 31 - 1 = 59
31 + 37 - 1 = 67
41 + 43 - 1 = 83
43 + 47 - 1 = 89
61 + 67 - 1 = 127
67 + 71 - 1 = 137
73 + 79 - 1 = 151
</pre>
==={{header|Tiny BASIC}}===
<syntaxhighlight lang="tinybasic"> REM B = SECOND OF THE NEIGBOURING PRIMES
REM C = P + B - 1
REM I = index variable
REM P = INPUT TO NEXTPRIME ROUTINE AND ISPRIME ROUTINE, also first of the two primes
REM T = Temporary variable, multiple uses
REM Z = OUTPUT OF ISPRIME, 1=prime, 0=not
LET P = 1
20 LET P = P + 2
IF P > 100 THEN END
GOSUB 100
IF Z = 0 THEN GOTO 20
GOSUB 120
IF B > 100 THEN END
LET T = P
LET P = P + B - 1
GOSUB 100
LET C = P
LET P = T
IF Z = 0 THEN GOTO 20
PRINT P," + ",B," - 1 = ", C
GOTO 20
100 REM PRIMALITY BY TRIAL DIVISION
LET Z = 1
LET I = 2
110 IF (P/I)*I = P THEN LET Z = 0
IF Z = 0 THEN RETURN
LET I = I + 1
IF I*I <= P THEN GOTO 110
RETURN
120 REM next prime after P
IF P < 2 THEN LET B = 2
IF P = 2 THEN LET B = 3
IF P < 3 THEN RETURN
LET T = P
130 LET P = P + 1
GOSUB 100
IF Z = 1 THEN GOTO 140
GOTO 130
140 LET B = P
LET P = T
RETURN</syntaxhighlight>
{{out}}<pre>
3 + 5 - 1 = 7
5 + 7 - 1 = 11
7 + 11 - 1 = 17
11 + 13 - 1 = 23
13 + 17 - 1 = 29
19 + 23 - 1 = 41
29 + 31 - 1 = 59
31 + 37 - 1 = 67
41 + 43 - 1 = 83
43 + 47 - 1 = 89
61 + 67 - 1 = 127
67 + 71 - 1 = 137
73 + 79 - 1 = 151
</pre>
Line 225 ⟶ 400:
73 + 79 - 1 = 151
</pre>
=={{header|Delphi}}==
{{works with|Delphi|6.0}}
{{libheader|SysUtils,StdCtrls}}
Uses the [[Extensible_prime_generator#Delphi|Delphi Prime-Generator Object]]
<syntaxhighlight lang="Delphi">
procedure SpecialNeighborPrimes(Memo: TMemo);
var I: integer;
var P1,P2: integer;
var Sieve: TPrimeSieve;
begin
Sieve:=TPrimeSieve.Create;
try
{Build more primes than we need}
Sieve.Intialize(200);
{Go through all primes}
for I:=1 to High(Sieve.Primes) do
begin
{Get neighbor primes}
P1:=Sieve.Primes[I-1];
P2:=Sieve.Primes[I];
{only test up to 100}
if P2>=100 then break;
{if P1+P2-1 is prime then display}
if Sieve.Flags[P1 + P2 - 1] then Memo.Lines.Add(Format('(%d, %d)',[P1,P2]));
end;
finally Sieve.Free; end;
end;
</syntaxhighlight>
{{out}}
<pre>
(3, 5)
(5, 7)
(7, 11)
(11, 13)
(13, 17)
(19, 23)
(29, 31)
(31, 37)
(41, 43)
(43, 47)
(61, 67)
(67, 71)
(73, 79)
Elapsed Time: 9.926 ms.
</pre>
Line 302 ⟶ 529:
67 + 71 - 1 = 137
73 + 79 - 1 = 151
</pre>
Line 420 ⟶ 608:
</pre>
=={{header|J}}==
<syntaxhighlight lang=
3 5 7
5 7 11
Line 479 ⟶ 622:
61 67 127
67 71 137
73 79 151</syntaxhighlight>
=={{header|jq}}==
{{works with|jq}}
Line 670 ⟶ 813:
</pre>
=={{header|PL/0}}==
PL/0 can only output a single integer per line, so to avoid confusing output, this sample just shows the first prime of each pair.
<br>
This is almost identical to the [[Neighbour primes#PL/0|PL/0 sample in the Neighbour primes task]]
<syntaxhighlight lang="pascal">
var n, p1, p2, prime;
procedure isnprime;
var p;
begin
prime := 1;
if n < 2 then prime := 0;
if n > 2 then begin
prime := 0;
if odd( n ) then prime := 1;
p := 3;
while p * p <= n * prime do begin
if n - ( ( n / p ) * p ) = 0 then prime := 0;
p := p + 2;
end
end
end;
begin
p1 := 3;
p2 := 5;
while p2 < 100 do begin
n := ( p1 + p2 ) - 1;
call isnprime;
if prime = 1 then ! p1;
n := p2 + 2;
call isnprime;
while prime = 0 do begin
n := n + 2;
call isnprime;
end;
p1 := p2;
p2 := n;
end
end.
</syntaxhighlight>
{{out}}
<pre>
3
5
7
11
13
19
29
31
41
43
61
67
73
</pre>
=={{header|PL/M}}==
{{works with|8080 PL/M Compiler}} ... under CP/M (or an emulator)
<syntaxhighlight lang="plm">
100H: /* FIND SOME PAIRS OF PRIMES P, Q BETWEEN 1 AND 99 SUCH THAT P + Q -1 */
/* IS ALSO A PRIME */
/* CP/M BDOS SYSTEM CALL AND I/O ROUTINES */
BDOS: PROCEDURE( FN, ARG ); DECLARE FN BYTE, ARG ADDRESS; GOTO 5; END;
PR$CHAR: PROCEDURE( C ); DECLARE C BYTE; CALL BDOS( 2, C ); END;
PR$STRING: PROCEDURE( S ); DECLARE S ADDRESS; CALL BDOS( 9, S ); END;
PR$NL: PROCEDURE; CALL PR$STRING( .( 0DH, 0AH, '$' ) ); END;
PR$NUMBER: PROCEDURE( N );
DECLARE N ADDRESS;
DECLARE V ADDRESS, N$STR( 6 ) BYTE, W BYTE;
V = N;
W = LAST( N$STR );
N$STR( W ) = '$';
N$STR( W := W - 1 ) = '0' + ( V MOD 10 );
DO WHILE( ( V := V / 10 ) > 0 );
N$STR( W := W - 1 ) = '0' + ( V MOD 10 );
END;
CALL PR$STRING( .N$STR( W ) );
END PR$NUMBER;
/* TASK */
DECLARE FALSE LITERALLY '0';
DECLARE TRUE LITERALLY '0FFH';
DECLARE MAX$LOW$PRIME LITERALLY '99';
DECLARE PRIME ( 200 )BYTE;
/* THE SIZE OF PRIME SHOULD BE AT LEAST MAX$LOW$PRIME DOUBLED */
/* SIEVE THE PRIMES TO MAX$PRIME */
DECLARE ( P, Q, COUNT ) ADDRESS;
PRIME( 1 ) = FALSE; PRIME( 2 ) = TRUE;
DO P = 3 TO LAST( PRIME ) BY 2; PRIME( P ) = TRUE; END;
DO P = 4 TO LAST( PRIME ) BY 2; PRIME( P ) = FALSE; END;
DO P = 3 TO MAX$LOW$PRIME + 1;
IF PRIME( P ) THEN DO;
DO Q = P * P TO LAST( PRIME ) BY P + P; PRIME( Q ) = FALSE; END;
END;
END;
/* FIND AND SHOW THE SPECIAL NEIGHBOUR PRIMES */
COUNT = 0;
P = 2;
Q = 3;
DO WHILE Q < MAX$LOW$PRIME;
IF PRIME( Q ) THEN DO;
DECLARE SNP ADDRESS;
SNP = P + Q - 1;
IF PRIME( SNP ) THEN DO;
/* P AND Q ARE SPECIAL NEIGHBOUR PRIMES */
CALL PR$STRING( .'( $' );
IF P < 10 THEN CALL PR$CHAR( ' ' );
CALL PR$NUMBER( P );
CALL PR$STRING( .' + $' );
IF Q < 10 THEN CALL PR$CHAR( ' ' );
CALL PR$NUMBER( Q );
CALL PR$STRING( .' ) - 1 = $' );
IF SNP < 100 THEN CALL PR$CHAR( ' ' );
IF SNP < 10 THEN CALL PR$CHAR( ' ' );
CALL PR$NUMBER( SNP );
CALL PR$NL;
END;
P = Q;
END;
Q = Q + 2;
END;
EOF
</syntaxhighlight>
{{out}}
<pre>
( 3 + 5 ) - 1 = 7
( 5 + 7 ) - 1 = 11
( 7 + 11 ) - 1 = 17
( 11 + 13 ) - 1 = 23
( 13 + 17 ) - 1 = 29
( 19 + 23 ) - 1 = 41
( 29 + 31 ) - 1 = 59
( 31 + 37 ) - 1 = 67
( 41 + 43 ) - 1 = 83
( 43 + 47 ) - 1 = 89
( 61 + 67 ) - 1 = 127
( 67 + 71 ) - 1 = 137
( 73 + 79 ) - 1 = 151
</pre>
=={{header|Python}}==
Line 711 ⟶ 997:
67 71 137
73 79 151</pre>
=={{header|Raku}}==
Line 838 ⟶ 1,123:
Found 13 special neighbor primes
done...
</pre>
=={{header|RPL}}==
{{works with|HP|49}}
≪ → max
≪ <span style="color:red">{ } 3 5</span>
'''DO'''
'''IF''' DUP2 + <span style="color:red">1</span> - ISPRIME? '''THEN''' DUP2 R→C <span style="color:red">4</span> ROLL SWAP + UNROT '''END'''
NIP DUP NEXTPRIME
'''UNTIL''' DUP max ≥ '''END'''
DROP2
≫ ≫ '<span style="color:blue">SNP</span>' STO
100 <span style="color:blue">SNP</span>
{{out}}
<pre>
1: { (3.,5.) (5.,7.) (7.,11.) (11.,13.) (13.,17.) (19.,23.) (29.,31.) (31.,37.) (41.,43.) (43.,47.) (61.,67.) (67.,71.) (73.,79.) }
</pre>
=={{header|Ruby}}==
<syntaxhighlight lang="ruby">require 'prime'
Prime.each(100).each_cons(2).select{|p1, p2|(p1+p2-1).prime?}.each{|ar| p ar}</syntaxhighlight>
{{out}}
<pre>[3, 5]
[5, 7]
[7, 11]
[11, 13]
[13, 17]
[19, 23]
[29, 31]
[31, 37]
[41, 43]
[43, 47]
[61, 67]
[67, 71]
[73, 79]
</pre>
Line 890 ⟶ 1,212:
Found 14526 special neighbour primes < 10^6
Found 103611 special neighbour primes < 10^7
</pre>
Line 957 ⟶ 1,218:
{{libheader|Wren-fmt}}
I assume that 'neighbor' primes means pairs of successive primes.
<syntaxhighlight lang="wren">import "./math" for Int
import "./fmt" for Fmt
var max = 1e7 - 1
| |||