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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 distuv
import (
"math/rand"
"sort"
"testing"
"gonum.org/v1/gonum/floats"
)
func TestChiSquaredProb(t *testing.T) {
for _, test := range []struct {
x, k, want float64
}{
{10, 3, 0.0085003666025203432},
{2.3, 3, 0.19157345407042367},
{0.8, 0.2, 0.080363259903912673},
} {
pdf := ChiSquared{test.k, nil}.Prob(test.x)
if !floats.EqualWithinAbsOrRel(pdf, test.want, 1e-10, 1e-10) {
t.Errorf("Pdf mismatch, x = %v, K = %v. Got %v, want %v", test.x, test.k, pdf, test.want)
}
}
}
func TestChiSquaredCDF(t *testing.T) {
for _, test := range []struct {
x, k, want float64
}{
// Values calculated with scipy.stats.chi2.cdf
{0, 1, 0},
{0.01, 5, 5.3002700426865167e-07},
{0.05, 3, 0.002929332764619924},
{0.5, 2, 0.22119921692859512},
{0.95, 3, 0.1866520918701263},
{0.99, 5, 0.036631697220869196},
{1, 1, 0.68268949213708596},
{1.5, 4, 0.17335853270322427},
{10, 10, 0.55950671493478743},
{25, 15, 0.95005656637357172},
} {
cdf := ChiSquared{test.k, nil}.CDF(test.x)
if !floats.EqualWithinAbsOrRel(cdf, test.want, 1e-10, 1e-10) {
t.Errorf("CDF mismatch, x = %v, K = %v. Got %v, want %v", test.x, test.k, cdf, test.want)
}
}
}
func TestChiSquared(t *testing.T) {
src := rand.New(rand.NewSource(1))
for i, b := range []ChiSquared{
{3, src},
{1.5, src},
{0.9, src},
} {
testChiSquared(t, b, i)
}
}
func testChiSquared(t *testing.T, c ChiSquared, i int) {
tol := 1e-2
const n = 2e6
const bins = 50
x := make([]float64, n)
generateSamples(x, c)
sort.Float64s(x)
testRandLogProbContinuous(t, i, 0, x, c, tol, bins)
checkMean(t, i, x, c, tol)
checkVarAndStd(t, i, x, c, tol)
checkExKurtosis(t, i, x, c, 5e-2)
checkProbContinuous(t, i, x, c, 1e-3)
checkQuantileCDFSurvival(t, i, x, c, 1e-3)
}