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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"
"gonum.org/v1/gonum/floats/scalar"
)
type Dorg2rer interface {
Dgeqrfer
Dorg2r(m, n, k int, a []float64, lda int, tau []float64, work []float64)
}
func Dorg2rTest(t *testing.T, impl Dorg2rer) {
rnd := rand.New(rand.NewSource(1))
for ti, test := range []struct {
m, n, k, lda int
}{
{3, 3, 0, 0},
{4, 3, 0, 0},
{3, 3, 2, 0},
{4, 3, 2, 0},
{5, 5, 0, 20},
{5, 5, 3, 20},
{10, 5, 0, 20},
{10, 5, 2, 20},
} {
m := test.m
n := test.n
lda := test.lda
if lda == 0 {
lda = test.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()
}
// Compute the QR decomposition of A.
tau := make([]float64, min(m, n))
work := make([]float64, 1)
impl.Dgeqrf(m, n, a, lda, tau, work, -1)
work = make([]float64, int(work[0]))
impl.Dgeqrf(m, n, a, lda, tau, work, len(work))
// Compute the matrix Q explicitly using the first k elementary reflectors.
k := test.k
if k == 0 {
k = n
}
q := constructQK("QR", m, n, k, a, lda, tau)
// Compute the matrix Q using Dorg2r.
impl.Dorg2r(m, n, k, a, lda, tau[:k], work)
// Check that the first n columns of both results match.
same := true
loop:
for i := 0; i < m; i++ {
for j := 0; j < n; j++ {
if !scalar.EqualWithinAbsOrRel(q.Data[i*q.Stride+j], a[i*lda+j], 1e-12, 1e-12) {
same = false
break loop
}
}
}
if !same {
t.Errorf("Case %v: Q mismatch", ti)
}
}
}
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