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author | Tianon Gravi <admwiggin@gmail.com> | 2015-01-15 12:50:40 -0700 |
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committer | Tianon Gravi <admwiggin@gmail.com> | 2015-01-15 12:50:40 -0700 |
commit | 2a0db60599fdd75b1bc3e297180fbe1282763759 (patch) | |
tree | 68d43c3e30d9ab961ddf6b7365201ca6b675b253 /src/math/hypot.go | |
parent | ef33cba3c8de6c431df56503df51fcd3a473c89e (diff) | |
parent | f154da9e12608589e8d5f0508f908a0c3e88a1bb (diff) | |
download | golang-2a0db60599fdd75b1bc3e297180fbe1282763759.tar.gz |
Merge tag 'upstream/1.4' into debian-experimental
* tag 'upstream/1.4':
Imported Upstream version 1.4
Diffstat (limited to 'src/math/hypot.go')
-rw-r--r-- | src/math/hypot.go | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/src/math/hypot.go b/src/math/hypot.go new file mode 100644 index 000000000..2087cb05b --- /dev/null +++ b/src/math/hypot.go @@ -0,0 +1,43 @@ +// 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) +} |