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Diffstat (limited to '')
-rw-r--r-- | src/math/mod.go | 52 |
1 files changed, 52 insertions, 0 deletions
diff --git a/src/math/mod.go b/src/math/mod.go new file mode 100644 index 0000000..6f24250 --- /dev/null +++ b/src/math/mod.go @@ -0,0 +1,52 @@ +// Copyright 2009-2010 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package 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 +func Mod(x, y float64) float64 { + if haveArchMod { + return archMod(x, y) + } + return mod(x, y) +} + +func mod(x, y float64) float64 { + if y == 0 || IsInf(x, 0) || IsNaN(x) || IsNaN(y) { + return NaN() + } + y = Abs(y) + + yfr, yexp := Frexp(y) + r := x + if x < 0 { + r = -x + } + + for r >= y { + rfr, rexp := Frexp(r) + if rfr < yfr { + rexp = rexp - 1 + } + r = r - Ldexp(y, rexp-yexp) + } + if x < 0 { + r = -r + } + return r +} |