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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-16 19:23:18 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-16 19:23:18 +0000 |
commit | 43a123c1ae6613b3efeed291fa552ecd909d3acf (patch) | |
tree | fd92518b7024bc74031f78a1cf9e454b65e73665 /src/math/remainder.go | |
parent | Initial commit. (diff) | |
download | golang-1.20-43a123c1ae6613b3efeed291fa552ecd909d3acf.tar.xz golang-1.20-43a123c1ae6613b3efeed291fa552ecd909d3acf.zip |
Adding upstream version 1.20.14.upstream/1.20.14upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/math/remainder.go')
-rw-r--r-- | src/math/remainder.go | 95 |
1 files changed, 95 insertions, 0 deletions
diff --git a/src/math/remainder.go b/src/math/remainder.go new file mode 100644 index 0000000..8e99345 --- /dev/null +++ b/src/math/remainder.go @@ -0,0 +1,95 @@ +// Copyright 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 + +// The original C code and the comment below are from +// FreeBSD's /usr/src/lib/msun/src/e_remainder.c and came +// with this notice. The go code is a simplified version of +// the original C. +// +// ==================================================== +// Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. +// +// Developed at SunPro, a Sun Microsystems, Inc. business. +// Permission to use, copy, modify, and distribute this +// software is freely granted, provided that this notice +// is preserved. +// ==================================================== +// +// __ieee754_remainder(x,y) +// Return : +// returns x REM y = x - [x/y]*y as if in infinite +// precision arithmetic, where [x/y] is the (infinite bit) +// integer nearest x/y (in half way cases, choose the even one). +// Method : +// Based on Mod() returning x - [x/y]chopped * y exactly. + +// Remainder returns the IEEE 754 floating-point remainder of x/y. +// +// Special cases are: +// +// Remainder(±Inf, y) = NaN +// Remainder(NaN, y) = NaN +// Remainder(x, 0) = NaN +// Remainder(x, ±Inf) = x +// Remainder(x, NaN) = NaN +func Remainder(x, y float64) float64 { + if haveArchRemainder { + return archRemainder(x, y) + } + return remainder(x, y) +} + +func remainder(x, y float64) float64 { + const ( + Tiny = 4.45014771701440276618e-308 // 0x0020000000000000 + HalfMax = MaxFloat64 / 2 + ) + // special cases + switch { + case IsNaN(x) || IsNaN(y) || IsInf(x, 0) || y == 0: + return NaN() + case IsInf(y, 0): + return x + } + sign := false + if x < 0 { + x = -x + sign = true + } + if y < 0 { + y = -y + } + if x == y { + if sign { + zero := 0.0 + return -zero + } + return 0 + } + if y <= HalfMax { + x = Mod(x, y+y) // now x < 2y + } + if y < Tiny { + if x+x > y { + x -= y + if x+x >= y { + x -= y + } + } + } else { + yHalf := 0.5 * y + if x > yHalf { + x -= y + if x >= yHalf { + x -= y + } + } + } + if sign { + x = -x + } + return x +} |