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