qbit/go
1
0
Fork 0
mirror of https://github.com/golang/go synced 2024-11-21 16:24:40 -07:00
Code Releases Activity

math: delete non-Sqrt-based Hypot

Browse Source 
I was confused by the existence of two portable Hypot
routines in the tree when I cleaned things up, and I made
ARM use the wrong (imprecise) one.  Use the right one,
and delete the wrong one.

Fixes arm build.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/5485065
This commit is contained in:
Russ Cox 2011-12-13 17:08:56 -05:00
parent 2c6d3eaf78
commit 2572803899
4 changed files with 10 additions and 74 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

34
src/pkg/math/all_test.go
View File

@ -2062,30 +2062,16 @@ func TestHypot(t *testing.T) {
}
}
func TestHypotSqrtGo(t *testing.T) {
func TestHypotGo(t *testing.T) {
for i := 0; i < len(vf); i++ {
a := Abs(1e200 * tanh[i] * Sqrt(2))
if f := HypotSqrtGo(1e200*tanh[i], 1e200*tanh[i]); !veryclose(a, f) {
t.Errorf("HypotSqrtGo(%g, %g) = %g, want %g", 1e200*tanh[i], 1e200*tanh[i], f, a)
if f := HypotGo(1e200*tanh[i], 1e200*tanh[i]); !veryclose(a, f) {
t.Errorf("HypotGo(%g, %g) = %g, want %g", 1e200*tanh[i], 1e200*tanh[i], f, a)
}
}
for i := 0; i < len(vfhypotSC); i++ {
if f := HypotSqrtGo(vfhypotSC[i][0], vfhypotSC[i][1]); !alike(hypotSC[i], f) {
t.Errorf("HypotSqrtGo(%g, %g) = %g, want %g", vfhypotSC[i][0], vfhypotSC[i][1], f, hypotSC[i])
}
}
}
func TestHypotNoSqrtGo(t *testing.T) {
for i := 0; i < len(vf); i++ {
a := Abs(1e200 * tanh[i] * Sqrt(2))
if f := HypotNoSqrtGo(1e200*tanh[i], 1e200*tanh[i]); !veryclose(a, f) {
t.Errorf("HypotNoSqrtGo(%g, %g) = %g, want %g", 1e200*tanh[i], 1e200*tanh[i], f, a)
}
}
for i := 0; i < len(vfhypotSC); i++ {
if f := HypotNoSqrtGo(vfhypotSC[i][0], vfhypotSC[i][1]); !alike(hypotSC[i], f) {
t.Errorf("HypotNoSqrtGo(%g, %g) = %g, want %g", vfhypotSC[i][0], vfhypotSC[i][1], f, hypotSC[i])
if f := HypotGo(vfhypotSC[i][0], vfhypotSC[i][1]); !alike(hypotSC[i], f) {
t.Errorf("HypotGo(%g, %g) = %g, want %g", vfhypotSC[i][0], vfhypotSC[i][1], f, hypotSC[i])
}
}
}
@ -2741,15 +2727,9 @@ func BenchmarkHypot(b *testing.B) {
}
}
func BenchmarkHypotNoSqrtGo(b *testing.B) {
func BenchmarkHypotGo(b *testing.B) {
for i := 0; i < b.N; i++ {
HypotNoSqrtGo(3, 4)
}
}
func BenchmarkHypotSqrtGo(b *testing.B) {
for i := 0; i < b.N; i++ {
HypotSqrtGo(3, 4)
HypotGo(3, 4)
}
}

3
src/pkg/math/export_test.go
View File

@ -7,6 +7,5 @@ package math
// Export internal functions for testing.
var ExpGo = exp
var Exp2Go = exp2
var HypotSqrtGo = hypotSqrt
var HypotNoSqrtGo = hypotNoSqrt
var HypotGo = hypot
var SqrtGo = sqrt

45
src/pkg/math/hypot.go
View File

@ -16,7 +16,7 @@ package math
// Hypot(p, q) = NaN if p or q is NaN
func Hypot(p, q float64) float64
func hypotSqrt(p, q float64) float64 {
func hypot(p, q float64) float64 {
// TODO(rsc): Remove manual inlining of IsNaN, IsInf
// when compiler does it for us
// special cases
@ -41,46 +41,3 @@ func hypotSqrt(p, q float64) float64 {
q = q / p
return p * Sqrt(1+q*q)
}
func hypotNoSqrt(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
}
pfac := p
q = q / p
r := q
p = 1
for {
r = r * r
s := r + 4
if s == 4 {
return p * pfac
}
r = r / s
p = p + 2*r*p
q = q * r
r = q / p
}
panic("unreachable")
}

2
src/pkg/math/hypot_arm.s
View File

@ -3,4 +3,4 @@
// license that can be found in the LICENSE file.
TEXT ·Hypot(SB),7,$0
B ·hypotNoSqrt(SB)
B ·hypot(SB)