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Source file src/math/hypot.go

  // Copyright 2010 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
  
  /*
  	Hypot -- sqrt(p*p + q*q), but overflows only if the result does.
  */
  
  // Hypot returns Sqrt(p*p + q*q), taking care to avoid
  // unnecessary overflow and underflow.
  //
  // Special cases are:
  //	Hypot(±Inf, q) = +Inf
  //	Hypot(p, ±Inf) = +Inf
  //	Hypot(NaN, q) = NaN
  //	Hypot(p, NaN) = NaN
  func Hypot(p, q float64) float64
  
  func hypot(p, q float64) float64 {
  	// special cases
  	switch {
  	case IsInf(p, 0) || IsInf(q, 0):
  		return Inf(1)
  	case IsNaN(p) || IsNaN(q):
  		return NaN()
  	}
  	if p < 0 {
  		p = -p
  	}
  	if q < 0 {
  		q = -q
  	}
  	if p < q {
  		p, q = q, p
  	}
  	if p == 0 {
  		return 0
  	}
  	q = q / p
  	return p * Sqrt(1+q*q)
  }
  

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