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Source file src/math/asin.go

Documentation: math

  // 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
  func Asin(x float64) float64
  
  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
  func Acos(x float64) float64
  
  func acos(x float64) float64 {
  	return Pi/2 - Asin(x)
  }
  

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