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authorupstream source tree <ports@midipix.org>2015-03-15 20:14:05 -0400
committerupstream source tree <ports@midipix.org>2015-03-15 20:14:05 -0400
commit554fd8c5195424bdbcabf5de30fdc183aba391bd (patch)
tree976dc5ab7fddf506dadce60ae936f43f58787092 /libgo/go/math/hypot.go
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Diffstat (limited to 'libgo/go/math/hypot.go')
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diff --git a/libgo/go/math/hypot.go b/libgo/go/math/hypot.go
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+// 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 {
+ // TODO(rsc): Remove manual inlining of IsNaN, IsInf
+ // when compiler does it for us
+ // special cases
+ switch {
+ case p < -MaxFloat64 || p > MaxFloat64 || q < -MaxFloat64 || q > MaxFloat64: // IsInf(p, 0) || IsInf(q, 0):
+ return Inf(1)
+ case p != p || q != q: // 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)
+}