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Diffstat (limited to 'v_windows/v/vlib/math/div.v')
-rw-r--r-- | v_windows/v/vlib/math/div.v | 87 |
1 files changed, 87 insertions, 0 deletions
diff --git a/v_windows/v/vlib/math/div.v b/v_windows/v/vlib/math/div.v new file mode 100644 index 0000000..6ad3c0d --- /dev/null +++ b/v_windows/v/vlib/math/div.v @@ -0,0 +1,87 @@ +module math + +// Floating-point mod function. +// mod returns the floating-point remainder of x/y. +// The magnitude of the result is less than y and its +// sign agrees with that of x. +// +// special cases are: +// mod(±inf, y) = nan +// mod(nan, y) = nan +// mod(x, 0) = nan +// mod(x, ±inf) = x +// mod(x, nan) = nan +pub fn mod(x f64, y f64) f64 { + return fmod(x, y) +} + +// fmod returns the floating-point remainder of number / denom (rounded towards zero) +pub fn fmod(x f64, y f64) f64 { + if y == 0 || is_inf(x, 0) || is_nan(x) || is_nan(y) { + return nan() + } + abs_y := abs(y) + abs_y_fr, abs_y_exp := frexp(abs_y) + mut r := x + if x < 0 { + r = -x + } + for r >= abs_y { + rfr, mut rexp := frexp(r) + if rfr < abs_y_fr { + rexp = rexp - 1 + } + r = r - ldexp(abs_y, rexp - abs_y_exp) + } + if x < 0 { + r = -r + } + return r +} + +// gcd calculates greatest common (positive) divisor (or zero if a and b are both zero). +pub fn gcd(a_ i64, b_ i64) i64 { + mut a := a_ + mut b := b_ + if a < 0 { + a = -a + } + if b < 0 { + b = -b + } + for b != 0 { + a %= b + if a == 0 { + return b + } + b %= a + } + return a +} + +// egcd returns (gcd(a, b), x, y) such that |a*x + b*y| = gcd(a, b) +pub fn egcd(a i64, b i64) (i64, i64, i64) { + mut old_r, mut r := a, b + mut old_s, mut s := i64(1), i64(0) + mut old_t, mut t := i64(0), i64(1) + + for r != 0 { + quot := old_r / r + old_r, r = r, old_r % r + old_s, s = s, old_s - quot * s + old_t, t = t, old_t - quot * t + } + return if old_r < 0 { -old_r } else { old_r }, old_s, old_t +} + +// lcm calculates least common (non-negative) multiple. +pub fn lcm(a i64, b i64) i64 { + if a == 0 { + return a + } + res := a * (b / gcd(b, a)) + if res < 0 { + return -res + } + return res +} |