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// Copyright ©2015 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"
)
type Dgebd2er interface {
Dgebd2(m, n int, a []float64, lda int, d, e, tauq, taup, work []float64)
}
func Dgebd2Test(t *testing.T, impl Dgebd2er) {
rnd := rand.New(rand.NewSource(1))
for _, test := range []struct {
m, n, lda int
}{
{3, 4, 0},
{4, 3, 0},
{3, 4, 10},
{4, 3, 10},
} {
m := test.m
n := test.n
lda := test.lda
if lda == 0 {
lda = n
}
// Allocate m×n 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)
// Allocate slices for the main and off diagonal.
nb := min(m, n)
d := nanSlice(nb)
e := nanSlice(nb - 1)
// Allocate slices for scalar factors of elementary reflectors
// and fill them with NaNs.
tauP := nanSlice(nb)
tauQ := nanSlice(nb)
// Allocate workspace.
work := nanSlice(max(m, n))
// Reduce A to upper or lower bidiagonal form by an orthogonal
// transformation.
impl.Dgebd2(m, n, a, lda, d, e, tauQ, tauP, work)
// Check that it holds Qᵀ * A * P = B where B is represented by
// d and e.
checkBidiagonal(t, m, n, nb, a, lda, d, e, tauP, tauQ, aCopy)
}
}
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