Complex Prime Number Test

[Eddie W. Shore]

Program:

Code:

EXPORT cisprime(z)
BEGIN
// 2014-11-09 EWS
LOCAL a,b,r,t;
a:=RE(z);
b:=IM(z);
r:=a^2+b^2;
IF CAS.isPrime(r)==1 THEN
t:=1; END;
IF a==0 AND ABS(b) MOD 4==3 AND CAS.isprime(ABS(b))==1 THEN
t:=1; END;
IF b==0 AND ABS(a) MOD 4==3 AND CAS.isprime(ABS(a))==1 THEN
t:=1; END;
RETURN t;
END;

(Edited 2014-11-13, see the thread - thanks Joe and Thomas!)


Examples:
cisprime(2-4*i) returns 0
cisprime(-2+5*i) returns 1

Source: http://mathworld.wolfram.com/GaussianPrime.html