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math: special cases for Hypot

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Added special case tests to all_test.go. Added tests to hypot.go,
otherwise hangs.

R=rsc
CC=golang-dev
https://golang.org/cl/186118
This commit is contained in:
Charles L. Dorian 2010-01-15 13:21:47 -08:00 committed by Russ Cox
parent 7f11db5ea9
commit 9a6b8e21e4
2 changed files with 97 additions and 26 deletions
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108
src/pkg/math/all_test.go
View File

@ -309,6 +309,41 @@ var fmodSC = []float64{
NaN(),
}
var vfhypotSC = [][2]float64{
[2]float64{Inf(-1), Inf(-1)},
[2]float64{Inf(-1), 0},
[2]float64{Inf(-1), Inf(1)},
[2]float64{Inf(-1), NaN()},
[2]float64{0, Inf(-1)},
[2]float64{0, Inf(1)},
[2]float64{0, NaN()},
[2]float64{Inf(1), Inf(-1)},
[2]float64{Inf(1), 0},
[2]float64{Inf(1), Inf(1)},
[2]float64{Inf(1), NaN()},
[2]float64{NaN(), Inf(-1)},
[2]float64{NaN(), 0},
[2]float64{NaN(), Inf(1)},
[2]float64{NaN(), NaN()},
}
var hypotSC = []float64{
Inf(1),
Inf(1),
Inf(1),
Inf(1),
Inf(1),
Inf(1),
NaN(),
Inf(1),
Inf(1),
Inf(1),
Inf(1),
Inf(1),
NaN(),
Inf(1),
NaN(),
}
var vflogSC = []float64{
Inf(-1),
-Pi,
@ -413,6 +448,19 @@ var powSC = []float64{
1,
}
var vfsqrtSC = []float64{
Inf(-1),
-Pi,
Inf(1),
NaN(),
}
var sqrtSC = []float64{
NaN(),
NaN(),
Inf(1),
NaN(),
}
func tolerance(a, b, e float64) bool {
d := a - b
if d < 0 {
@ -525,12 +573,26 @@ func TestFloor(t *testing.T) {
func TestFmod(t *testing.T) {
for i := 0; i < len(vf); i++ {
if f := Fmod(10, vf[i]); !close(fmod[i], f) {
t.Errorf("Fmod(10, %.17g) = %.17g, want %.17g\n", vf[i], f, fmod[i])
t.Errorf("Fmod(10, %g) = %g, want %g\n", vf[i], f, fmod[i])
}
}
for i := 0; i < len(vffmodSC); i++ {
if f := Fmod(vffmodSC[i][0], vffmodSC[i][1]); !alike(fmodSC[i], f) {
t.Errorf("Fmod(%.17g, %.17g) = %.17g, want %.17g\n", vffmodSC[i][0], vffmodSC[i][1], f, fmodSC[i])
t.Errorf("Fmod(%g, %g) = %g, want %g\n", vffmodSC[i][0], vffmodSC[i][1], f, fmodSC[i])
}
}
}
func TestHypot(t *testing.T) {
for i := 0; i < len(vf); i++ {
a := Fabs(tanh[i] * Sqrt(2))
if f := Hypot(tanh[i], tanh[i]); a != f {
t.Errorf("Hypot(%g, %g) = %g, want %g\n", tanh[i], tanh[i], f, a)
}
}
for i := 0; i < len(vfhypotSC); i++ {
if f := Hypot(vfhypotSC[i][0], vfhypotSC[i][1]); !alike(hypotSC[i], f) {
t.Errorf("Hypot(%g, %g) = %g, want %g\n", vfhypotSC[i][0], vfhypotSC[i][1], f, hypotSC[i])
}
}
}
@ -572,12 +634,12 @@ func TestLog10(t *testing.T) {
func TestPow(t *testing.T) {
for i := 0; i < len(vf); i++ {
if f := Pow(10, vf[i]); !close(pow[i], f) {
t.Errorf("Pow(10, %.17g) = %.17g, want %.17g\n", vf[i], f, pow[i])
t.Errorf("Pow(10, %g) = %g, want %g\n", vf[i], f, pow[i])
}
}
for i := 0; i < len(vfpowSC); i++ {
if f := Pow(vfpowSC[i][0], vfpowSC[i][1]); !alike(powSC[i], f) {
t.Errorf("Pow(%.17g, %.17g) = %.17g, want %.17g\n", vfpowSC[i][0], vfpowSC[i][1], f, powSC[i])
t.Errorf("Pow(%g, %g) = %g, want %g\n", vfpowSC[i][0], vfpowSC[i][1], f, powSC[i])
}
}
}
@ -609,6 +671,11 @@ func TestSqrt(t *testing.T) {
t.Errorf("Sqrt(%g) = %g, want %g\n", a, f, sqrt[i])
}
}
for i := 0; i < len(vfsqrtSC); i++ {
if f := Log10(vfsqrtSC[i]); !alike(sqrtSC[i], f) {
t.Errorf("Sqrt(%g) = %g, want %g\n", vfsqrtSC[i], f, sqrtSC[i])
}
}
}
func TestTan(t *testing.T) {
@ -627,15 +694,6 @@ func TestTanh(t *testing.T) {
}
}
func TestHypot(t *testing.T) {
for i := 0; i < len(vf); i++ {
a := Fabs(tanh[i] * Sqrt(2))
if f := Hypot(tanh[i], tanh[i]); a != f {
t.Errorf("Hypot(%g, %g) = %g, want %g\n", tanh[i], tanh[i], f, a)
}
}
}
// Check that math functions of high angle values
// return similar results to low angle values
func TestLargeSin(t *testing.T) {
@ -700,18 +758,6 @@ func TestFloatMinMax(t *testing.T) {
// Benchmarks
func BenchmarkPowInt(b *testing.B) {
for i := 0; i < b.N; i++ {
Pow(2, 2)
}
}
func BenchmarkPowFrac(b *testing.B) {
for i := 0; i < b.N; i++ {
Pow(2.5, 1.5)
}
}
func BenchmarkAtan(b *testing.B) {
for i := 0; i < b.N; i++ {
Atan(.5)
@ -730,6 +776,18 @@ func BenchmarkAcos(b *testing.B) {
}
}
func BenchmarkPowInt(b *testing.B) {
for i := 0; i < b.N; i++ {
Pow(2, 2)
}
}
func BenchmarkPowFrac(b *testing.B) {
for i := 0; i < b.N; i++ {
Pow(2.5, 1.5)
}
}
func BenchmarkSqrt(b *testing.B) {
for i := 0; i < b.N; i++ {
Sqrt(10)

15
src/pkg/math/hypot.go
View File

@ -1,4 +1,4 @@
// Copyright 2009 The Go Authors. All rights reserved.
// Copyright 2009-2010 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.
@ -15,7 +15,20 @@ package math
// 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
}