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author | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
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committer | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
commit | 554fd8c5195424bdbcabf5de30fdc183aba391bd (patch) | |
tree | 976dc5ab7fddf506dadce60ae936f43f58787092 /libgo/go/math/asin.go | |
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Diffstat (limited to 'libgo/go/math/asin.go')
-rw-r--r-- | libgo/go/math/asin.go | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/libgo/go/math/asin.go b/libgo/go/math/asin.go new file mode 100644 index 000000000..3bace8ff1 --- /dev/null +++ b/libgo/go/math/asin.go @@ -0,0 +1,50 @@ +// 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 of x. +// +// Special cases are: +// Asin(±0) = ±0 +// Asin(x) = NaN if x < -1 or x > 1 +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 of x. +// +// Special case is: +// Acos(x) = NaN if x < -1 or x > 1 +func Acos(x float64) float64 { return Pi/2 - Asin(x) } |