math: atan2 special cases (negative zero)
Added Signbit(), revised Copysign()
R=rsc
CC=golang-dev
https://golang.org/cl/822045
diff --git a/src/pkg/math/all_test.go b/src/pkg/math/all_test.go
index 2f133f1..fed60ed 100644
--- a/src/pkg/math/all_test.go
+++ b/src/pkg/math/all_test.go
@@ -466,6 +466,18 @@
8.734595415957246977711748e-01,
1.314075231424398637614104e+00,
}
+var signbit = []bool{
+ false,
+ false,
+ true,
+ true,
+ false,
+ false,
+ false,
+ false,
+ false,
+ true,
+}
var sin = []float64{
-9.6466616586009283766724726e-01,
9.9338225271646545763467022e-01,
@@ -653,8 +665,16 @@
[2]float64{-Pi, 0},
[2]float64{-Pi, Inf(1)},
[2]float64{-Pi, NaN()},
+ [2]float64{-1 / Inf(1), Inf(-1)}, // -0, -Inf
+ [2]float64{-1 / Inf(1), -Pi}, // -0, -Pi
+ [2]float64{-1 / Inf(1), -1 / Inf(1)}, // -0, -0
+ [2]float64{-1 / Inf(1), 0}, // -0, +0
+ [2]float64{-1 / Inf(1), +Pi}, // -0, +Pi
+ [2]float64{-1 / Inf(1), Inf(1)}, // -0, +Inf
+ [2]float64{-1 / Inf(1), NaN()}, // -0, NaN
[2]float64{0, Inf(-1)},
[2]float64{0, -Pi},
+ [2]float64{0, -1 / Inf(1)}, // +0, -0
[2]float64{0, 0},
[2]float64{0, +Pi},
[2]float64{0, Inf(1)},
@@ -680,10 +700,18 @@
NaN(),
-Pi,
-Pi / 2,
- -0,
+ -1 / Inf(1), // -0
+ NaN(),
+ -Pi,
+ -Pi,
+ -Pi, // -0, -0
+ -1 / Inf(1),
+ -1 / Inf(1),
+ -1 / Inf(1),
NaN(),
Pi,
Pi,
+ Pi, // +0, -0
0,
0,
0,
@@ -1107,6 +1135,21 @@
1,
}
+var vfsignbitSC = []float64{
+ Inf(-1),
+ -1 / Inf(1), // -0
+ 1 / Inf(1), // +0
+ Inf(1),
+ NaN(),
+}
+var signbitSC = []bool{
+ true,
+ true,
+ false,
+ false,
+ false,
+}
+
var vfsqrtSC = []float64{
Inf(-1),
-Pi,
@@ -1174,7 +1217,7 @@
case IsNaN(a) && IsNaN(b):
return true
case a == b:
- return true
+ return Signbit(a) == Signbit(b)
}
return false
}
@@ -1705,6 +1748,18 @@
}
}
+func TestSignbit(t *testing.T) {
+ for i := 0; i < len(vf); i++ {
+ if f := Signbit(vf[i]); signbit[i] != f {
+ t.Errorf("Signbit(%g) = %t, want %t\n", vf[i], f, signbit[i])
+ }
+ }
+ for i := 0; i < len(vfsignbitSC); i++ {
+ if f := Signbit(vfsignbitSC[i]); signbitSC[i] != f {
+ t.Errorf("Signbit(%g) = %t, want %t\n", vfsignbitSC[i], vfsignbitSC[i], f, signbitSC[i])
+ }
+ }
+}
func TestSin(t *testing.T) {
for i := 0; i < len(vf); i++ {
if f := Sin(vf[i]); !close(sin[i], f) {
@@ -2150,6 +2205,12 @@
}
}
+func BenchmarkSignbit(b *testing.B) {
+ for i := 0; i < b.N; i++ {
+ Signbit(2.5)
+ }
+}
+
func BenchmarkSin(b *testing.B) {
for i := 0; i < b.N; i++ {
Sin(.5)
