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52 lines
1.4 KiB
Go
52 lines
1.4 KiB
Go
// Copyright ©2017 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 testlapack
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import (
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"testing"
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"golang.org/x/exp/rand"
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"gonum.org/v1/gonum/floats/scalar"
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"gonum.org/v1/gonum/lapack"
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)
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type Dlapller interface {
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Dgesvder
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Dlapll(n int, x []float64, incX int, y []float64, incY int) float64
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}
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func DlapllTest(t *testing.T, impl Dlapller) {
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rnd := rand.New(rand.NewSource(1))
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for i, m := range []int{5, 6, 9, 300, 400, 600} {
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n := 2
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lda := n
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// Allocate m×2 matrix A and fill it with random numbers.
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a := make([]float64, m*lda)
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for i := range a {
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a[i] = rnd.NormFloat64()
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}
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// Store a copy of A for later comparison.
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aCopy := make([]float64, len(a))
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copy(aCopy, a)
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// Compute the smallest singular value of A.
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got := impl.Dlapll(m, a[0:], lda, a[1:], lda)
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// Compute singular values of A independently by Dgesvd.
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s := make([]float64, min(m, n))
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work := make([]float64, 1)
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impl.Dgesvd(lapack.SVDNone, lapack.SVDNone, m, n, aCopy, lda, s, nil, 1, nil, 1, work, -1)
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work = make([]float64, int(work[0]))
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impl.Dgesvd(lapack.SVDNone, lapack.SVDNone, m, n, aCopy, lda, s, nil, 1, nil, 1, work, len(work))
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// Take the smallest singular value.
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want := s[len(s)-1]
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if !scalar.EqualWithinAbsOrRel(got, want, 1e-14, 1e-14) {
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t.Errorf("Case %d: unexpected smallest singular value, got:%f want:%f", i, got, want)
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}
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}
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}
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