github.com/jingcheng-WU/gonum@v0.9.1-0.20210323123734-f1a2a11a8f7b/lapack/testlapack/dorg2r.go (about)

     1  // Copyright ©2015 The Gonum Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package testlapack
     6  
     7  import (
     8  	"testing"
     9  
    10  	"golang.org/x/exp/rand"
    11  
    12  	"github.com/jingcheng-WU/gonum/floats/scalar"
    13  )
    14  
    15  type Dorg2rer interface {
    16  	Dgeqrfer
    17  	Dorg2r(m, n, k int, a []float64, lda int, tau []float64, work []float64)
    18  }
    19  
    20  func Dorg2rTest(t *testing.T, impl Dorg2rer) {
    21  	rnd := rand.New(rand.NewSource(1))
    22  	for ti, test := range []struct {
    23  		m, n, k, lda int
    24  	}{
    25  		{3, 3, 0, 0},
    26  		{4, 3, 0, 0},
    27  		{3, 3, 2, 0},
    28  		{4, 3, 2, 0},
    29  
    30  		{5, 5, 0, 20},
    31  		{5, 5, 3, 20},
    32  		{10, 5, 0, 20},
    33  		{10, 5, 2, 20},
    34  	} {
    35  		m := test.m
    36  		n := test.n
    37  		lda := test.lda
    38  		if lda == 0 {
    39  			lda = test.n
    40  		}
    41  		// Allocate m×n matrix A and fill it with random numbers.
    42  		a := make([]float64, m*lda)
    43  		for i := range a {
    44  			a[i] = rnd.NormFloat64()
    45  		}
    46  
    47  		// Compute the QR decomposition of A.
    48  		tau := make([]float64, min(m, n))
    49  		work := make([]float64, 1)
    50  		impl.Dgeqrf(m, n, a, lda, tau, work, -1)
    51  		work = make([]float64, int(work[0]))
    52  		impl.Dgeqrf(m, n, a, lda, tau, work, len(work))
    53  
    54  		// Compute the matrix Q explicitly using the first k elementary reflectors.
    55  		k := test.k
    56  		if k == 0 {
    57  			k = n
    58  		}
    59  		q := constructQK("QR", m, n, k, a, lda, tau)
    60  
    61  		// Compute the matrix Q using Dorg2r.
    62  		impl.Dorg2r(m, n, k, a, lda, tau, work)
    63  
    64  		// Check that the first n columns of both results match.
    65  		same := true
    66  	loop:
    67  		for i := 0; i < m; i++ {
    68  			for j := 0; j < n; j++ {
    69  				if !scalar.EqualWithinAbsOrRel(q.Data[i*q.Stride+j], a[i*lda+j], 1e-12, 1e-12) {
    70  					same = false
    71  					break loop
    72  				}
    73  			}
    74  		}
    75  		if !same {
    76  			t.Errorf("Case %v: Q mismatch", ti)
    77  		}
    78  	}
    79  }