gcc/libgo/go/math/hypot.go
Ian Lance Taylor dd931d9b48 libgo: update to Go 1.11
Reviewed-on: https://go-review.googlesource.com/136435

gotools/:
	* Makefile.am (mostlyclean-local): Run chmod on check-go-dir to
	make sure it is writable.
	(check-go-tools): Likewise.
	(check-vet): Copy internal/objabi to check-vet-dir.
	* Makefile.in: Rebuild.

From-SVN: r264546
2018-09-24 21:46:21 +00:00

41 lines
797 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 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 {
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()
}
p, q = Abs(p), Abs(q)
if p < q {
p, q = q, p
}
if p == 0 {
return 0
}
q = q / p
return p * Sqrt(1+q*q)
}