mirror of git://gcc.gnu.org/git/gcc.git
68 lines
1.1 KiB
Go
68 lines
1.1 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 arcsine and arccosine.
|
|
|
|
They are implemented by computing the arctangent
|
|
after appropriate range reduction.
|
|
*/
|
|
|
|
// Asin returns the arcsine, in radians, of x.
|
|
//
|
|
// Special cases are:
|
|
// Asin(±0) = ±0
|
|
// Asin(x) = NaN if x < -1 or x > 1
|
|
|
|
//extern asin
|
|
func libc_asin(float64) float64
|
|
|
|
func Asin(x float64) float64 {
|
|
return libc_asin(x)
|
|
}
|
|
|
|
func asin(x float64) float64 {
|
|
if x == 0 {
|
|
return x // special case
|
|
}
|
|
sign := false
|
|
if x < 0 {
|
|
x = -x
|
|
sign = true
|
|
}
|
|
if x > 1 {
|
|
return NaN() // special case
|
|
}
|
|
|
|
temp := Sqrt(1 - x*x)
|
|
if x > 0.7 {
|
|
temp = Pi/2 - satan(temp/x)
|
|
} else {
|
|
temp = satan(x / temp)
|
|
}
|
|
|
|
if sign {
|
|
temp = -temp
|
|
}
|
|
return temp
|
|
}
|
|
|
|
// Acos returns the arccosine, in radians, of x.
|
|
//
|
|
// Special case is:
|
|
// Acos(x) = NaN if x < -1 or x > 1
|
|
|
|
//extern acos
|
|
func libc_acos(float64) float64
|
|
|
|
func Acos(x float64) float64 {
|
|
return libc_acos(x)
|
|
}
|
|
|
|
func acos(x float64) float64 {
|
|
return Pi/2 - Asin(x)
|
|
}
|