summaryrefslogtreecommitdiffstats
path: root/src/math/sincos.go
diff options
context:
space:
mode:
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/sincos.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/sincos.go')
-rw-r--r--src/math/sincos.go72
1 files changed, 72 insertions, 0 deletions
diff --git a/src/math/sincos.go b/src/math/sincos.go
new file mode 100644
index 0000000..5c5726f
--- /dev/null
+++ b/src/math/sincos.go
@@ -0,0 +1,72 @@
+// 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
+
+// Coefficients _sin[] and _cos[] are found in pkg/math/sin.go.
+
+// Sincos returns Sin(x), Cos(x).
+//
+// Special cases are:
+// Sincos(±0) = ±0, 1
+// Sincos(±Inf) = NaN, NaN
+// Sincos(NaN) = NaN, NaN
+func Sincos(x float64) (sin, cos float64) {
+ const (
+ PI4A = 7.85398125648498535156e-1 // 0x3fe921fb40000000, Pi/4 split into three parts
+ PI4B = 3.77489470793079817668e-8 // 0x3e64442d00000000,
+ PI4C = 2.69515142907905952645e-15 // 0x3ce8469898cc5170,
+ )
+ // special cases
+ switch {
+ case x == 0:
+ return x, 1 // return ±0.0, 1.0
+ case IsNaN(x) || IsInf(x, 0):
+ return NaN(), NaN()
+ }
+
+ // make argument positive
+ sinSign, cosSign := false, false
+ if x < 0 {
+ x = -x
+ sinSign = true
+ }
+
+ var j uint64
+ var y, z float64
+ if x >= reduceThreshold {
+ j, z = trigReduce(x)
+ } else {
+ j = uint64(x * (4 / Pi)) // integer part of x/(Pi/4), as integer for tests on the phase angle
+ y = float64(j) // integer part of x/(Pi/4), as float
+
+ if j&1 == 1 { // map zeros to origin
+ j++
+ y++
+ }
+ j &= 7 // octant modulo 2Pi radians (360 degrees)
+ z = ((x - y*PI4A) - y*PI4B) - y*PI4C // Extended precision modular arithmetic
+ }
+ if j > 3 { // reflect in x axis
+ j -= 4
+ sinSign, cosSign = !sinSign, !cosSign
+ }
+ if j > 1 {
+ cosSign = !cosSign
+ }
+
+ zz := z * z
+ cos = 1.0 - 0.5*zz + zz*zz*((((((_cos[0]*zz)+_cos[1])*zz+_cos[2])*zz+_cos[3])*zz+_cos[4])*zz+_cos[5])
+ sin = z + z*zz*((((((_sin[0]*zz)+_sin[1])*zz+_sin[2])*zz+_sin[3])*zz+_sin[4])*zz+_sin[5])
+ if j == 1 || j == 2 {
+ sin, cos = cos, sin
+ }
+ if cosSign {
+ cos = -cos
+ }
+ if sinSign {
+ sin = -sin
+ }
+ return
+}