mirror of
https://github.com/gonum/gonum.git
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88 lines
2.0 KiB
Go
88 lines
2.0 KiB
Go
// Copyright ©2015 The Gonum Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package quad
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import (
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"math"
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"testing"
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"gonum.org/v1/gonum/floats"
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"gonum.org/v1/gonum/floats/scalar"
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)
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func TestLegendre(t *testing.T) {
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t.Parallel()
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for i, test := range []struct {
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f func(float64) float64
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min, max float64
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n []int
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tol []float64
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ans float64
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}{
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// Tolerances determined from intuition and a bit of post-hoc tweaking.
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{
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f: func(x float64) float64 { return math.Exp(x) },
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min: -3,
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max: 5,
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n: []int{3, 4, 6, 7, 15, 16, 300, 301},
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tol: []float64{5e-2, 5e-3, 5e-6, 1e-7, 1e-14, 1e-14, 1e-14, 1e-14},
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ans: math.Exp(5) - math.Exp(-3),
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},
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} {
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for j, n := range test.n {
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ans := Fixed(test.f, test.min, test.max, n, Legendre{}, 0)
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if !scalar.EqualWithinAbsOrRel(ans, test.ans, test.tol[j], test.tol[j]) {
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t.Errorf("Mismatch. Case = %d, n = %d. Want %v, got %v", i, n, test.ans, ans)
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}
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ans2 := Fixed(test.f, test.min, test.max, n, Legendre{}, 3)
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if !scalar.EqualWithinAbsOrRel(ans2, test.ans, test.tol[j], test.tol[j]) {
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t.Errorf("Mismatch concurrent. Case = %d, n = %d. Want %v, got %v", i, n, test.ans, ans)
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}
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}
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}
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}
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func TestLegendreSingle(t *testing.T) {
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t.Parallel()
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for c, test := range []struct {
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n int
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min, max float64
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}{
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{
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n: 100,
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min: -1,
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max: 1,
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},
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{
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n: 50,
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min: -3,
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max: -1,
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},
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{
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n: 1000,
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min: 2,
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max: 7,
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},
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} {
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l := Legendre{}
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n := test.n
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xs := make([]float64, n)
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weights := make([]float64, n)
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l.FixedLocations(xs, weights, test.min, test.max)
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xsSingle := make([]float64, n)
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weightsSingle := make([]float64, n)
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for i := range xsSingle {
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xsSingle[i], weightsSingle[i] = l.FixedLocationSingle(n, i, test.min, test.max)
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}
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if !floats.Equal(xs, xsSingle) {
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t.Errorf("Case %d: xs mismatch batch and single", c)
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}
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if !floats.Equal(weights, weightsSingle) {
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t.Errorf("Case %d: weights mismatch batch and single", c)
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}
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}
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}
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