| // Copyright ©2016 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 ( |
| "fmt" |
| "testing" |
| |
| "golang.org/x/exp/rand" |
| |
| "gonum.org/v1/gonum/blas" |
| "gonum.org/v1/gonum/blas/blas64" |
| "gonum.org/v1/gonum/floats" |
| ) |
| |
| type Dorgtrer interface { |
| Dorgtr(uplo blas.Uplo, n int, a []float64, lda int, tau, work []float64, lwork int) |
| Dsytrder |
| } |
| |
| func DorgtrTest(t *testing.T, impl Dorgtrer) { |
| const tol = 1e-14 |
| |
| rnd := rand.New(rand.NewSource(1)) |
| for _, uplo := range []blas.Uplo{blas.Upper, blas.Lower} { |
| for _, wl := range []worklen{minimumWork, mediumWork, optimumWork} { |
| for _, test := range []struct { |
| n, lda int |
| }{ |
| {1, 0}, |
| {2, 0}, |
| {3, 0}, |
| {6, 0}, |
| {33, 0}, |
| {100, 0}, |
| |
| {1, 3}, |
| {2, 5}, |
| {3, 7}, |
| {6, 10}, |
| {33, 50}, |
| {100, 120}, |
| } { |
| n := test.n |
| lda := test.lda |
| if lda == 0 { |
| lda = n |
| } |
| // Allocate n×n matrix A and fill it with random numbers. |
| a := make([]float64, n*lda) |
| for i := range a { |
| a[i] = rnd.NormFloat64() |
| } |
| aCopy := make([]float64, len(a)) |
| copy(aCopy, a) |
| |
| // Allocate slices for the main diagonal and the |
| // first off-diagonal of the tri-diagonal matrix. |
| d := make([]float64, n) |
| e := make([]float64, n-1) |
| // Allocate slice for elementary reflector scales. |
| tau := make([]float64, n-1) |
| |
| // Compute optimum workspace size for Dorgtr call. |
| work := make([]float64, 1) |
| impl.Dsytrd(uplo, n, a, lda, d, e, tau, work, -1) |
| work = make([]float64, int(work[0])) |
| |
| // Compute elementary reflectors that reduce the |
| // symmetric matrix defined by the uplo triangle |
| // of A to a tridiagonal matrix. |
| impl.Dsytrd(uplo, n, a, lda, d, e, tau, work, len(work)) |
| |
| // Compute workspace size for Dorgtr call. |
| var lwork int |
| switch wl { |
| case minimumWork: |
| lwork = max(1, n-1) |
| case mediumWork: |
| work := make([]float64, 1) |
| impl.Dorgtr(uplo, n, a, lda, tau, work, -1) |
| lwork = (int(work[0]) + n - 1) / 2 |
| lwork = max(1, lwork) |
| case optimumWork: |
| work := make([]float64, 1) |
| impl.Dorgtr(uplo, n, a, lda, tau, work, -1) |
| lwork = int(work[0]) |
| } |
| work = nanSlice(lwork) |
| |
| // Generate an orthogonal matrix Q that reduces |
| // the uplo triangle of A to a tridiagonal matrix. |
| impl.Dorgtr(uplo, n, a, lda, tau, work, len(work)) |
| q := blas64.General{ |
| Rows: n, |
| Cols: n, |
| Stride: lda, |
| Data: a, |
| } |
| |
| name := fmt.Sprintf("uplo=%c,n=%v,lda=%v,work=%v", uplo, n, lda, wl) |
| |
| if resid := residualOrthogonal(q, false); resid > tol*float64(n) { |
| t.Errorf("Case %v: Q is not orthogonal; resid=%v, want<=%v", name, resid, tol*float64(n)) |
| } |
| |
| // Create the tridiagonal matrix explicitly in |
| // dense representation from the diagonals d and e. |
| tri := blas64.General{ |
| Rows: n, |
| Cols: n, |
| Stride: n, |
| Data: make([]float64, n*n), |
| } |
| for i := 0; i < n; i++ { |
| tri.Data[i*tri.Stride+i] = d[i] |
| if i != n-1 { |
| tri.Data[i*tri.Stride+i+1] = e[i] |
| tri.Data[(i+1)*tri.Stride+i] = e[i] |
| } |
| } |
| |
| // Create the symmetric matrix A from the uplo |
| // triangle of aCopy, storing it explicitly in dense form. |
| aMat := blas64.General{ |
| Rows: n, |
| Cols: n, |
| Stride: n, |
| Data: make([]float64, n*n), |
| } |
| if uplo == blas.Upper { |
| for i := 0; i < n; i++ { |
| for j := i; j < n; j++ { |
| v := aCopy[i*lda+j] |
| aMat.Data[i*aMat.Stride+j] = v |
| aMat.Data[j*aMat.Stride+i] = v |
| } |
| } |
| } else { |
| for i := 0; i < n; i++ { |
| for j := 0; j <= i; j++ { |
| v := aCopy[i*lda+j] |
| aMat.Data[i*aMat.Stride+j] = v |
| aMat.Data[j*aMat.Stride+i] = v |
| } |
| } |
| } |
| |
| // Compute Qᵀ * A * Q and store the result in ans. |
| tmp := blas64.General{Rows: n, Cols: n, Stride: n, Data: make([]float64, n*n)} |
| blas64.Gemm(blas.NoTrans, blas.NoTrans, 1, aMat, q, 0, tmp) |
| ans := blas64.General{Rows: n, Cols: n, Stride: n, Data: make([]float64, n*n)} |
| blas64.Gemm(blas.Trans, blas.NoTrans, 1, q, tmp, 0, ans) |
| |
| // Compare the tridiagonal matrix tri from |
| // Dorgtr with the explicit computation ans. |
| if !floats.EqualApprox(ans.Data, tri.Data, tol) { |
| t.Errorf("Case %v: Recombination mismatch", name) |
| } |
| } |
| } |
| } |
| } |