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// Copyright ©2016 The Gonum 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 mathext
import (
"math"
"testing"
"gonum.org/v1/gonum/floats/scalar"
)
var result float64
func TestDigamma(t *testing.T) {
t.Parallel()
const tol = 1e-10
for i, test := range []struct {
x, want float64
}{
// Results computed using WolframAlpha.
{0.0, math.Inf(-1)},
{math.Copysign(0.0, -1.0), math.Inf(1)},
{math.Inf(1), math.Inf(1)},
{math.Inf(-1), math.NaN()},
{math.NaN(), math.NaN()},
{-1.0, math.NaN()},
{-100.5, 4.615124601338064117341315601525112558522917517910505881343},
{0.5, -1.96351002602142347944097633299875556719315960466043},
{10, 2.251752589066721107647456163885851537211808918028330369448},
{math.Pow10(20), 46.05170185988091368035482909368728415202202143924212618733},
{-1.111111111e9, math.NaN()},
{1.46, -0.001580561987083417676105544023567034348339520110000},
} {
got := Digamma(test.x)
if !(math.IsNaN(got) && math.IsNaN(test.want)) && !scalar.EqualWithinAbsOrRel(got, test.want, tol, tol) {
t.Errorf("test %d Digamma(%g) failed: got %g want %g", i, test.x, got, test.want)
}
}
}
func BenchmarkDigamma(b *testing.B) {
var r float64
for i := 0; i < b.N; i++ {
r = Digamma(-1.111111111e9)
}
result = r
}
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