The GIfactor function returns the Gaussian integer factorization of c.

The answer is in the form:  such that  where  is one of four units,  are the distinct primary prime factors of c, and  are their multiplicities.

The number  of the four associated primes , , ,  is singled out as primary in which we have simultaneously either () or ().

The expand function may be applied to cause the factors to be multiplied together again.