math: fix pow10 comment, test portable Sqrt

R=r
CC= golang-dev, Charlie Dorian, golang-dev
https://golang.org/cl/184058

src/pkg/math/all_test.go

@@ -307,7 +307,6 @@ func alike(a, b float64) bool {
 
 func TestAcos(t *testing.T) {
 	for i := 0; i < len(vf); i++ {
-		//		if f := Acos(vf[i] / 10); !veryclose(acos[i], f) {
 		if f := Acos(vf[i] / 10); !close(acos[i], f) {
 			t.Errorf("Acos(%g) = %g, want %g\n", vf[i]/10, f, acos[i])
 		}
@@ -405,8 +404,12 @@ func TestSinh(t *testing.T) {
 func TestSqrt(t *testing.T) {
 	for i := 0; i < len(vf); i++ {
 		a := Fabs(vf[i])
-		if f := Sqrt(a); !veryclose(sqrt[i], f) {
-			t.Errorf("Sqrt(%g) = %g, want %g\n", a, f, floor[i])
+		if f := SqrtGo(a); sqrt[i] != f {
+			t.Errorf("sqrtGo(%g) = %g, want %g\n", a, f, sqrt[i])
+		}
+		a = Fabs(vf[i])
+		if f := Sqrt(a); sqrt[i] != f {
+			t.Errorf("Sqrt(%g) = %g, want %g\n", a, f, sqrt[i])
 		}
 	}
 }
@@ -430,7 +433,7 @@ 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]); !veryclose(a, f) {
+		if f := Hypot(tanh[i], tanh[i]); a != f {
 			t.Errorf("Hypot(%g, %g) = %g, want %g\n", tanh[i], tanh[i], f, a)
 		}
 	}

src/pkg/math/pow10.go

@@ -15,7 +15,7 @@ package math
 
 var pow10tab [70]float64
 
-// Pow10 returns 10**x, the base-10 exponential of x.
+// Pow10 returns 10**e, the base-10 exponential of e.
 func Pow10(e int) float64 {
 	if e < 0 {
 		return 1 / Pow10(-e)

src/pkg/math/sqrt_test.go

+// 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
+
+// Make sqrtGo available for testing.
+
+func SqrtGo(x float64) float64 { return sqrtGo(x) }