gonum.org/v1/gonum@v0.15.1-0.20240517103525-f853624cb1bb/lapack/testlapack/dgeqrf.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  	"gonum.org/v1/gonum/floats"
    13  )
    14  
    15  type Dgeqrfer interface {
    16  	Dgeqr2er
    17  	Dgeqrf(m, n int, a []float64, lda int, tau, work []float64, lwork int)
    18  }
    19  
    20  func DgeqrfTest(t *testing.T, impl Dgeqrfer) {
    21  	const tol = 1e-12
    22  	rnd := rand.New(rand.NewSource(1))
    23  	for c, test := range []struct {
    24  		m, n, lda int
    25  	}{
    26  		{10, 5, 0},
    27  		{5, 10, 0},
    28  		{10, 10, 0},
    29  		{300, 5, 0},
    30  		{3, 500, 0},
    31  		{200, 200, 0},
    32  		{300, 200, 0},
    33  		{204, 300, 0},
    34  		{1, 3000, 0},
    35  		{3000, 1, 0},
    36  		{10, 5, 20},
    37  		{5, 10, 20},
    38  		{10, 10, 20},
    39  		{300, 5, 400},
    40  		{3, 500, 600},
    41  		{200, 200, 300},
    42  		{300, 200, 300},
    43  		{204, 300, 400},
    44  		{1, 3000, 4000},
    45  		{3000, 1, 4000},
    46  	} {
    47  		m := test.m
    48  		n := test.n
    49  		lda := test.lda
    50  		if lda == 0 {
    51  			lda = test.n
    52  		}
    53  
    54  		// Allocate m×n matrix A and fill it with random numbers.
    55  		a := make([]float64, m*lda)
    56  		for i := range a {
    57  			a[i] = rnd.NormFloat64()
    58  		}
    59  		// Store a copy of A for later comparison.
    60  		aCopy := make([]float64, len(a))
    61  		copy(aCopy, a)
    62  
    63  		// Allocate a slice for scalar factors of elementary reflectors
    64  		// and fill it with random numbers.
    65  		k := min(m, n)
    66  		tau := make([]float64, k)
    67  		for i := range tau {
    68  			tau[i] = rnd.Float64()
    69  		}
    70  
    71  		// Compute the expected result using unblocked QR algorithm and
    72  		// store it in want.
    73  		want := make([]float64, len(a))
    74  		copy(want, a)
    75  		impl.Dgeqr2(m, n, want, lda, tau, make([]float64, n))
    76  
    77  		for _, wl := range []worklen{minimumWork, mediumWork, optimumWork} {
    78  			copy(a, aCopy)
    79  
    80  			var lwork int
    81  			switch wl {
    82  			case minimumWork:
    83  				lwork = n
    84  			case mediumWork:
    85  				work := make([]float64, 1)
    86  				impl.Dgeqrf(m, n, a, lda, tau, work, -1)
    87  				lwork = int(work[0]) - 2*n
    88  			case optimumWork:
    89  				work := make([]float64, 1)
    90  				impl.Dgeqrf(m, n, a, lda, tau, work, -1)
    91  				lwork = int(work[0])
    92  			}
    93  			work := make([]float64, lwork)
    94  
    95  			// Compute the QR factorization of A.
    96  			impl.Dgeqrf(m, n, a, lda, tau, work, len(work))
    97  			// Compare the result with Dgeqr2.
    98  			if !floats.EqualApprox(want, a, tol) {
    99  				t.Errorf("Case %v, workspace %v, unexpected result.", c, wl)
   100  			}
   101  		}
   102  	}
   103  }