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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/blas/blas64" ) func TestDlagsy(t *testing.T) { const tol = 1e-14 rnd := rand.New(rand.NewSource(1)) for _, n := range []int{0, 1, 2, 3, 4, 5, 10, 50} { for _, lda := range []int{0, 2*n + 1} { if lda == 0 { lda = max(1, n) } // D is the identity matrix I. d := make([]float64, n) for i := range d { d[i] = 1 } // Allocate an n×n symmetric matrix A and fill it with NaNs. a := nanSlice(n * lda) work := make([]float64, 2*n) // Compute A = U * D * Uᵀ where U is a random orthogonal matrix. Dlagsy(n, 0, d, a, lda, rnd, work) // A should be the identity matrix because // A = U * D * Uᵀ = U * I * Uᵀ = U * Uᵀ = I. dist := distFromIdentity(n, a, lda) if dist > tol { t.Errorf("Case n=%v,lda=%v: |A-I|=%v is too large", n, lda, dist) } } } } func TestDlagge(t *testing.T) { const tol = 1e-14 rnd := rand.New(rand.NewSource(1)) for _, n := range []int{0, 1, 2, 3, 4, 5, 10, 50} { for _, lda := range []int{0, 2*n + 1} { if lda == 0 { lda = max(1, n) } d := make([]float64, n) for i := range d { d[i] = 1 } a := blas64.General{ Rows: n, Cols: n, Stride: lda, Data: nanSlice(n * lda), } work := make([]float64, a.Rows+a.Cols) Dlagge(a.Rows, a.Cols, 0, 0, d, a.Data, a.Stride, rnd, work) if resid := residualOrthogonal(a, false); resid > tol { t.Errorf("Case n=%v,lda=%v: unexpected result", n, lda) } } } } func TestRandomOrthogonal(t *testing.T) { const tol = 1e-14 rnd := rand.New(rand.NewSource(1)) for n := 1; n <= 20; n++ { q := randomOrthogonal(n, rnd) if resid := residualOrthogonal(q, false); resid > tol { t.Errorf("Case n=%v: Q not orthogonal; resid=%v, want<=%v", n, resid, tol) } } }