math: add Gamma function
R=rsc
CC=golang-dev
https://golang.org/cl/649041
diff --git a/src/pkg/math/all_test.go b/src/pkg/math/all_test.go
index 8cb5756..b28a1f4 100644
--- a/src/pkg/math/all_test.go
+++ b/src/pkg/math/all_test.go
@@ -286,6 +286,18 @@
fi{9.1265404584042750000e-01, 1},
fi{-5.4287029803597508250e-01, 4},
}
+var gamma = []float64{
+ 2.3254348370739963835386613898e+01,
+ 2.991153837155317076427529816e+03,
+ -4.561154336726758060575129109e+00,
+ 7.719403468842639065959210984e-01,
+ 1.6111876618855418534325755566e+05,
+ 1.8706575145216421164173224946e+00,
+ 3.4082787447257502836734201635e+01,
+ 1.579733951448952054898583387e+00,
+ 9.3834586598354592860187267089e-01,
+ -2.093995902923148389186189429e-05,
+}
var lgamma = []fi{
fi{3.146492141244545774319734e+00, 1},
fi{8.003414490659126375852113e+00, 1},
@@ -736,6 +748,21 @@
fi{NaN(), 0},
}
+var vfgammaSC = []float64{
+ Inf(-1),
+ -3,
+ 0,
+ Inf(1),
+ NaN(),
+}
+var gammaSC = []float64{
+ Inf(-1),
+ Inf(1),
+ Inf(1),
+ Inf(1),
+ NaN(),
+}
+
var vfhypotSC = [][2]float64{
[2]float64{Inf(-1), Inf(-1)},
[2]float64{Inf(-1), 0},
@@ -1278,6 +1305,19 @@
}
}
+func TestGamma(t *testing.T) {
+ for i := 0; i < len(vf); i++ {
+ if f := Gamma(vf[i]); !close(gamma[i], f) {
+ t.Errorf("Gamma(%g) = %g, want %g\n", vf[i], f, gamma[i])
+ }
+ }
+ for i := 0; i < len(vfgammaSC); i++ {
+ if f := Gamma(vfgammaSC[i]); !alike(gammaSC[i], f) {
+ t.Errorf("Gamma(%g) = %g, want %g\n", vfgammaSC[i], f, gammaSC[i])
+ }
+ }
+}
+
func TestHypot(t *testing.T) {
for i := 0; i < len(vf); i++ {
a := Fabs(1e200 * tanh[i] * Sqrt(2))
@@ -1748,6 +1788,12 @@
}
}
+func BenchmarkGamma(b *testing.B) {
+ for i := 0; i < b.N; i++ {
+ Gamma(2.5)
+ }
+}
+
func BenchmarkHypot(b *testing.B) {
for i := 0; i < b.N; i++ {
Hypot(3, 4)
