Example #1
0
File: int.go Project: locusf/gmp
// MulRange sets z to the product of all integers
// in the range [a, b] inclusively and returns z.
// If a > b (empty range), the result is 1.
func (z *Int) MulRange(a, b int64) *Int {
	switch {
	case a > b:
		return z.SetInt64(1) // empty range
	case a <= 0 && b >= 0:
		return z.SetInt64(0) // range includes 0
	}
	// a <= b && (b < 0 || a > 0)

	// Can use gmp factorial routine if a = 1 and b >= 1
	if a == 1 && b >= 1 {
		C.mpz_fac_ui(&z.i[0], C.ulong(b))
	} else {
		// Slow
		z.SetInt64(a)
		for i := a + 1; i <= b; i++ {
			C.mpz_mul_si(&z.i[0], &z.i[0], C.long(i))
		}
	}
	return z
}
Example #2
0
File: int_extra.go Project: ncw/gmp
// MulInt32 sets z to the product x*y and returns z.
//
// NB This is not part of big.Int
func (z *Int) MulInt32(x *Int, y int32) *Int {
	x.doinit()
	z.doinit()
	C.mpz_mul_si(&z.i[0], &x.i[0], C.long(y))
	return z
}