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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-28 13:14:23 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-28 13:14:23 +0000
commit73df946d56c74384511a194dd01dbe099584fd1a (patch)
treefd0bcea490dd81327ddfbb31e215439672c9a068 /src/math/remainder.go
parentInitial commit. (diff)
downloadgolang-1.16-73df946d56c74384511a194dd01dbe099584fd1a.tar.xz
golang-1.16-73df946d56c74384511a194dd01dbe099584fd1a.zip
Adding upstream version 1.16.10.upstream/1.16.10upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/math/remainder.go')
-rw-r--r--src/math/remainder.go89
1 files changed, 89 insertions, 0 deletions
diff --git a/src/math/remainder.go b/src/math/remainder.go
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+// 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
+
+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
+}