Retro68/gcc/libgo/go/math/hypot.go
Wolfgang Thaller aaf905ce07 add gcc 4.70
2012-03-28 01:13:14 +02:00

44 lines
807 B
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 computes Sqrt(p*p + q*q), taking care to avoid
// unnecessary overflow and underflow.
//
// Special cases are:
// Hypot(p, q) = +Inf if p or q is infinite
// Hypot(p, q) = NaN if p or q is NaN
func Hypot(p, q float64) float64 {
return hypot(p, q)
}
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)
}