1 // Copyright ©2016 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.
12 "golang.org/x/exp/rand"
14 "gonum.org/v1/gonum/blas"
15 "gonum.org/v1/gonum/blas/blas64"
18 type Dgehd2er interface {
19 Dgehd2(n, ilo, ihi int, a []float64, lda int, tau, work []float64)
22 func Dgehd2Test(t *testing.T, impl Dgehd2er) {
23 rnd := rand.New(rand.NewSource(1))
24 for _, n := range []int{1, 2, 3, 4, 5, 7, 10, 30} {
25 for _, extra := range []int{0, 1, 13} {
26 for cas := 0; cas < 100; cas++ {
27 testDgehd2(t, impl, n, extra, rnd)
33 func testDgehd2(t *testing.T, impl Dgehd2er, n, extra int, rnd *rand.Rand) {
40 tau := nanSlice(n - 1)
43 a := randomGeneral(n, n, n+extra, rnd)
44 // NaN out elements under the diagonal except
45 // for the [ilo:ihi,ilo:ihi] block.
46 for i := 1; i <= ihi; i++ {
47 for j := 0; j < min(ilo, i); j++ {
48 a.Data[i*a.Stride+j] = math.NaN()
51 for i := ihi + 1; i < n; i++ {
52 for j := 0; j < i; j++ {
53 a.Data[i*a.Stride+j] = math.NaN()
57 aCopy.Data = make([]float64, len(a.Data))
58 copy(aCopy.Data, a.Data)
60 impl.Dgehd2(n, ilo, ihi, a.Data, a.Stride, tau, work)
62 prefix := fmt.Sprintf("Case n=%v, ilo=%v, ihi=%v, extra=%v", n, ilo, ihi, extra)
64 // Check any invalid modifications of a.
65 if !generalOutsideAllNaN(a) {
66 t.Errorf("%v: out-of-range write to A\n%v", prefix, a.Data)
68 for i := ilo; i <= ihi; i++ {
69 for j := 0; j < min(ilo, i); j++ {
70 if !math.IsNaN(a.Data[i*a.Stride+j]) {
71 t.Errorf("%v: expected NaN at A[%v,%v]", prefix, i, j)
75 for i := ihi + 1; i < n; i++ {
76 for j := 0; j < i; j++ {
77 if !math.IsNaN(a.Data[i*a.Stride+j]) {
78 t.Errorf("%v: expected NaN at A[%v,%v]", prefix, i, j)
82 for i := 0; i <= ilo; i++ {
83 for j := i; j < ilo+1; j++ {
84 if a.Data[i*a.Stride+j] != aCopy.Data[i*aCopy.Stride+j] {
85 t.Errorf("%v: unexpected modification at A[%v,%v]", prefix, i, j)
88 for j := ihi + 1; j < n; j++ {
89 if a.Data[i*a.Stride+j] != aCopy.Data[i*aCopy.Stride+j] {
90 t.Errorf("%v: unexpected modification at A[%v,%v]", prefix, i, j)
94 for i := ihi + 1; i < n; i++ {
95 for j := i; j < n; j++ {
96 if a.Data[i*a.Stride+j] != aCopy.Data[i*aCopy.Stride+j] {
97 t.Errorf("%v: unexpected modification at A[%v,%v]", prefix, i, j)
102 // Check that tau has been assigned properly.
103 for i, v := range tau {
104 if i < ilo || i >= ihi {
106 t.Errorf("%v: expected NaN at tau[%v]", prefix, i)
110 t.Errorf("%v: unexpected NaN at tau[%v]", prefix, i)
115 // Extract Q and check that it is orthogonal.
120 Data: make([]float64, n*n),
122 for i := 0; i < q.Rows; i++ {
123 q.Data[i*q.Stride+i] = 1
126 qCopy.Data = make([]float64, len(q.Data))
127 for j := ilo; j < ihi; j++ {
132 Data: make([]float64, n*n),
134 for i := 0; i < h.Rows; i++ {
135 h.Data[i*h.Stride+i] = 1
139 Data: make([]float64, n),
142 for i := j + 2; i < ihi+1; i++ {
143 v.Data[i] = a.Data[i*a.Stride+j]
145 blas64.Ger(-tau[j], v, v, h)
146 copy(qCopy.Data, q.Data)
147 blas64.Gemm(blas.NoTrans, blas.NoTrans, 1, qCopy, h, 0, q)
149 if !isOrthonormal(q) {
150 t.Errorf("%v: Q is not orthogonal\nQ=%v", prefix, q)
153 // Overwrite NaN elements of aCopy with zeros
154 // (we will multiply with it below).
155 for i := 1; i <= ihi; i++ {
156 for j := 0; j < min(ilo, i); j++ {
157 aCopy.Data[i*aCopy.Stride+j] = 0
160 for i := ihi + 1; i < n; i++ {
161 for j := 0; j < i; j++ {
162 aCopy.Data[i*aCopy.Stride+j] = 0
166 // Construct Q^T * AOrig * Q and check that it is
167 // equal to A from Dgehd2.
168 aq := blas64.General{
172 Data: make([]float64, n*n),
174 blas64.Gemm(blas.NoTrans, blas.NoTrans, 1, aCopy, q, 0, aq)
175 qaq := blas64.General{
179 Data: make([]float64, n*n),
181 blas64.Gemm(blas.Trans, blas.NoTrans, 1, q, aq, 0, qaq)
182 for i := ilo; i <= ihi; i++ {
183 for j := ilo; j <= ihi; j++ {
184 qaqij := qaq.Data[i*qaq.Stride+j]
186 if math.Abs(qaqij) > 1e-14 {
187 t.Errorf("%v: Q^T*A*Q is not upper Hessenberg, [%v,%v]=%v", prefix, i, j, qaqij)
191 diff := qaqij - a.Data[i*a.Stride+j]
192 if math.Abs(diff) > 1e-14 {
193 t.Errorf("%v: Q^T*AOrig*Q and A are not equal, diff at [%v,%v]=%v", prefix, i, j, diff)