diff options
author | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
---|---|---|
committer | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
commit | 554fd8c5195424bdbcabf5de30fdc183aba391bd (patch) | |
tree | 976dc5ab7fddf506dadce60ae936f43f58787092 /libgo/go/math/sin.go | |
download | cbb-gcc-4.6.4-15d2061ac0796199866debe9ac87130894b0cdd3.tar.bz2 cbb-gcc-4.6.4-15d2061ac0796199866debe9ac87130894b0cdd3.tar.xz |
obtained gcc-4.6.4.tar.bz2 from upstream website;upstream
verified gcc-4.6.4.tar.bz2.sig;
imported gcc-4.6.4 source tree from verified upstream tarball.
downloading a git-generated archive based on the 'upstream' tag
should provide you with a source tree that is binary identical
to the one extracted from the above tarball.
if you have obtained the source via the command 'git clone',
however, do note that line-endings of files in your working
directory might differ from line-endings of the respective
files in the upstream repository.
Diffstat (limited to 'libgo/go/math/sin.go')
-rw-r--r-- | libgo/go/math/sin.go | 66 |
1 files changed, 66 insertions, 0 deletions
diff --git a/libgo/go/math/sin.go b/libgo/go/math/sin.go new file mode 100644 index 000000000..35220cb3e --- /dev/null +++ b/libgo/go/math/sin.go @@ -0,0 +1,66 @@ +// Copyright 2009 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 sine and cosine. + + Coefficients are #5077 from Hart & Cheney. (18.80D) +*/ + +func sinus(x float64, quad int) float64 { + const ( + P0 = .1357884097877375669092680e8 + P1 = -.4942908100902844161158627e7 + P2 = .4401030535375266501944918e6 + P3 = -.1384727249982452873054457e5 + P4 = .1459688406665768722226959e3 + Q0 = .8644558652922534429915149e7 + Q1 = .4081792252343299749395779e6 + Q2 = .9463096101538208180571257e4 + Q3 = .1326534908786136358911494e3 + ) + if x < 0 { + x = -x + quad = quad + 2 + } + x = x * (2 / Pi) /* underflow? */ + var y float64 + if x > 32764 { + var e float64 + e, y = Modf(x) + e = e + float64(quad) + f, _ := Modf(0.25 * e) + quad = int(e - 4*f) + } else { + k := int32(x) + y = x - float64(k) + quad = (quad + int(k)) & 3 + } + + if quad&1 != 0 { + y = 1 - y + } + if quad > 1 { + y = -y + } + + yy := y * y + temp1 := ((((P4*yy+P3)*yy+P2)*yy+P1)*yy + P0) * y + temp2 := ((((yy+Q3)*yy+Q2)*yy+Q1)*yy + Q0) + return temp1 / temp2 +} + +// Cos returns the cosine of x. +func Cos(x float64) float64 { + if x < 0 { + x = -x + } + return sinus(x, 1) +} + +// Sin returns the sine of x. +func Sin(x float64) float64 { return sinus(x, 0) } |