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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/nextafter.go
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Diffstat (limited to 'libgo/go/math/nextafter.go')
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diff --git a/libgo/go/math/nextafter.go b/libgo/go/math/nextafter.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
+
+// Nextafter returns the next representable value after x towards y.
+// If x == y, then x is returned.
+//
+// Special cases are:
+// Nextafter(NaN, y) = NaN
+// Nextafter(x, NaN) = NaN
+func Nextafter(x, y float64) (r float64) {
+ // TODO(rsc): Remove manual inlining of IsNaN
+ // when compiler does it for us
+ switch {
+ case x != x || y != y: // IsNaN(x) || IsNaN(y): // special case
+ r = NaN()
+ case x == y:
+ r = x
+ case x == 0:
+ r = Copysign(Float64frombits(1), y)
+ case (y > x) == (x > 0):
+ r = Float64frombits(Float64bits(x) + 1)
+ default:
+ r = Float64frombits(Float64bits(x) - 1)
+ }
+ return r
+}