gcc/libgo/go/math/sin.go
Ian Lance Taylor 7a9389330e Add Go frontend, libgo library, and Go testsuite.
gcc/:
	* gcc.c (default_compilers): Add entry for ".go".
	* common.opt: Add -static-libgo as a driver option.
	* doc/install.texi (Configuration): Mention libgo as an option for
	--enable-shared.  Mention go as an option for --enable-languages.
	* doc/invoke.texi (Overall Options): Mention .go as a file name
	suffix.  Mention go as a -x option.
	* doc/frontends.texi (G++ and GCC): Mention Go as a supported
	language.
	* doc/sourcebuild.texi (Top Level): Mention libgo.
	* doc/standards.texi (Standards): Add section on Go language.
	Move references for other languages into their own section.
	* doc/contrib.texi (Contributors): Mention that I contributed the
	Go frontend.
gcc/testsuite/:
	* lib/go.exp: New file.
	* lib/go-dg.exp: New file.
	* lib/go-torture.exp: New file.
	* lib/target-supports.exp (check_compile): Match // Go.

From-SVN: r167407
2010-12-03 04:34:57 +00:00

67 lines
1.3 KiB
Go

// 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) }