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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 testlapack import ( "math" "testing" "golang.org/x/exp/rand" "gonum.org/v1/gonum/lapack" ) type Dlanster interface { Dlanst(norm lapack.MatrixNorm, n int, d, e []float64) float64 Dlanger } func DlanstTest(t *testing.T, impl Dlanster) { rnd := rand.New(rand.NewSource(1)) for _, norm := range []lapack.MatrixNorm{lapack.MaxAbs, lapack.MaxColumnSum, lapack.MaxRowSum, lapack.Frobenius} { for _, n := range []int{1, 3, 10, 100} { for cas := 0; cas < 100; cas++ { // Generate randomly the main diagonal of the // symmetric tridiagonal matrix A. d := make([]float64, n) for i := range d { d[i] = rnd.NormFloat64() } // Generate randomly the off-diagonal of A. e := make([]float64, n-1) for i := range e { e[i] = rnd.NormFloat64() } // Create A in dense representation. m := n lda := n a := make([]float64, m*lda) for i := 0; i < n; i++ { a[i*lda+i] = d[i] } for i := 0; i < n-1; i++ { a[i*lda+i+1] = e[i] a[(i+1)*lda+i] = e[i] } work := make([]float64, n) // Compute a norm of A using Dlanst. syNorm := impl.Dlanst(norm, n, d, e) // Compute a reference value for the norm using // Dlange and the dense representation of A. geNorm := impl.Dlange(norm, m, n, a, lda, work) if math.Abs(syNorm-geNorm) > 1e-12 { t.Errorf("Norm mismatch: norm = %v, cas = %v, n = %v. Want %v, got %v.", string(norm), cas, n, geNorm, syNorm) } } } } }