// Exp sets z = x^y % m and returns z.
// If m == nil, Exp sets z = x^y.
func (z *Int) Exp(x, y, m *Int) *Int {
m.doinit()
x.doinit()
y.doinit()
z.doinit()
if m == nil {
C.mpz_pow_ui(&z.i[0], &x.i[0], C.mpz_get_ui(&y.i[0]))
} else {
C.mpz_powm(&z.i[0], &x.i[0], &y.i[0], &m.i[0])
}
return z
}
// Exp sets z = x^y % m and returns z. If m != nil, negative exponents are
// allowed if x^-1 mod m exists. If the inverse doesn't exist then a
// division-by-zero run-time panic occurs.
//
// If m == nil, Exp sets z = x^y for positive y and 1 for negative y.
func (z *Int) Exp(x, y, m *Int) *Int {
x.doinit()
y.doinit()
z.doinit()
if m == nil || m.Cmp(intZero) == 0 {
if y.Sign() == -1 {
z := NewInt(1)
return z
}
C.mpz_pow_ui(z.ptr, x.ptr, C.mpz_get_ui(y.ptr))
} else {
m.doinit()
C.mpz_powm(z.ptr, x.ptr, y.ptr, m.ptr)
}
return z
}
// Exp sets z = x**y mod |m| (i.e. the sign of m is ignored), and returns z.
// If y <= 0, the result is 1; if m == nil or m == 0, z = x**y.
// See Knuth, volume 2, section 4.6.3.
func (z *Int) Exp(x, y, m *Int) *Int {
x.doinit()
y.doinit()
z.doinit()
if y.Sign() <= 0 {
z.SetInt64(1)
return z
}
if m == nil || m.Sign() == 0 {
C.mpz_pow_ui(&z.i[0], &x.i[0], C.mpz_get_ui(&y.i[0]))
} else {
m.doinit()
C.mpz_powm(&z.i[0], &x.i[0], &y.i[0], &m.i[0])
}
return z
}