testlapack: rewrite test for Dsytrd to remove its dependence on Dsytd2

Dsytd2 is not provided by LAPACKE and using blockedTranslate eliminates the
possibility to test the work slice.

testlapack/dsytrd.go

@@ -10,71 +10,150 @@ import (
 	"testing"
 
 	"github.com/gonum/blas"
-	"github.com/gonum/floats"
+	"github.com/gonum/blas/blas64"
 )
 
 type Dsytrder interface {
 	Dsytrd(uplo blas.Uplo, n int, a []float64, lda int, d, e, tau, work []float64, lwork int)
-	Dsytd2er
+
+	Dorgqr(m, n, k int, a []float64, lda int, tau, work []float64, lwork int)
+	Dorgql(m, n, k int, a []float64, lda int, tau, work []float64, lwork int)
 }
 
 func DsytrdTest(t *testing.T, impl Dsytrder) {
+	const tol = 1e-13
 	rnd := rand.New(rand.NewSource(1))
-	for _, uplo := range []blas.Uplo{blas.Upper, blas.Lower} {
-		for _, test := range []struct {
+	for tc, test := range []struct {
 		n, lda int
 	}{
+		{1, 0},
+		{2, 0},
+		{3, 0},
+		{4, 0},
 		{10, 0},
 		{50, 0},
 		{100, 0},
 		{150, 0},
 		{300, 0},
 
+		{1, 3},
+		{2, 3},
+		{3, 7},
+		{4, 9},
 		{10, 20},
 		{50, 70},
 		{100, 120},
 		{150, 170},
 		{300, 320},
 	} {
+		for _, uplo := range []blas.Uplo{blas.Upper, blas.Lower} {
+			for _, wl := range []worklen{minimumWork, mediumWork, optimumWork} {
 				n := test.n
 				lda := test.lda
 				if lda == 0 {
 					lda = n
 				}
-			a := make([]float64, n*lda)
-			for i := range a {
-				a[i] = rnd.NormFloat64()
+				a := randomGeneral(n, n, lda, rnd)
+				for i := 1; i < n; i++ {
+					for j := 0; j < i; j++ {
+						a.Data[i*a.Stride+j] = a.Data[j*a.Stride+i]
 					}
-			d2 := make([]float64, n)
-			e2 := make([]float64, n)
-			tau2 := make([]float64, n)
+				}
+				aCopy := cloneGeneral(a)
 
-			aCopy := make([]float64, len(a))
-			copy(aCopy, a)
-			impl.Dsytd2(uplo, n, a, lda, d2, e2, tau2)
-			aAns := make([]float64, len(a))
-			copy(aAns, a)
+				d := nanSlice(n)
+				e := nanSlice(n - 1)
+				tau := nanSlice(n - 1)
 
-			copy(a, aCopy)
-			d := make([]float64, n)
-			e := make([]float64, n)
-			tau := make([]float64, n)
+				var lwork int
+				switch wl {
+				case minimumWork:
+					lwork = 1
+				case mediumWork:
 					work := make([]float64, 1)
-			impl.Dsytrd(uplo, n, a, lda, d, e, tau, work, -1)
-			work = make([]float64, int(work[0]))
-			impl.Dsytrd(uplo, n, a, lda, d, e, tau, work, len(work))
-			errStr := fmt.Sprintf("upper = %v, n = %v", uplo == blas.Upper, n)
-			if !floats.EqualApprox(a, aAns, 1e-8) {
-				t.Errorf("A mismatch: %s", errStr)
+					impl.Dsytrd(uplo, n, a.Data, a.Stride, d, e, tau, work, -1)
+					lwork = (int(work[0]) + 1) / 2
+					lwork = max(1, lwork)
+				case optimumWork:
+					work := make([]float64, 1)
+					impl.Dsytrd(uplo, n, a.Data, a.Stride, d, e, tau, work, -1)
+					lwork = int(work[0])
 				}
-			if !floats.EqualApprox(d, d2, 1e-8) {
-				t.Errorf("D mismatch: %s", errStr)
+				work := make([]float64, lwork)
+
+				impl.Dsytrd(uplo, n, a.Data, a.Stride, d, e, tau, work, lwork)
+
+				prefix := fmt.Sprintf("Case #%v: uplo=%v,n=%v,lda=%v,work=%v",
+					tc, uplo, n, lda, wl)
+
+				if !generalOutsideAllNaN(a) {
+					t.Errorf("%v: out-of-range write to A", prefix)
 				}
-			if !floats.EqualApprox(e, e2, 1e-8) {
-				t.Errorf("E mismatch: %s", errStr)
+
+				// Extract Q by doing what Dorgtr does.
+				q := cloneGeneral(a)
+				if uplo == blas.Upper {
+					for j := 0; j < n-1; j++ {
+						for i := 0; i < j; i++ {
+							q.Data[i*q.Stride+j] = q.Data[i*q.Stride+j+1]
+						}
+						q.Data[(n-1)*q.Stride+j] = 0
+					}
+					for i := 0; i < n-1; i++ {
+						q.Data[i*q.Stride+n-1] = 0
+					}
+					q.Data[(n-1)*q.Stride+n-1] = 1
+					if n > 1 {
+						work = make([]float64, n-1)
+						impl.Dorgql(n-1, n-1, n-1, q.Data, q.Stride, tau, work, len(work))
+					}
+				} else {
+					for j := n - 1; j > 0; j-- {
+						q.Data[j] = 0
+						for i := j + 1; i < n; i++ {
+							q.Data[i*q.Stride+j] = q.Data[i*q.Stride+j-1]
+						}
+					}
+					q.Data[0] = 1
+					for i := 1; i < n; i++ {
+						q.Data[i*q.Stride] = 0
+					}
+					if n > 1 {
+						work = make([]float64, n-1)
+						impl.Dorgqr(n-1, n-1, n-1, q.Data[q.Stride+1:], q.Stride, tau, work, len(work))
+					}
+				}
+				if !isOrthonormal(q) {
+					t.Errorf("%v: Q not orthogonal", prefix)
+				}
+
+				// Contruct symmetric tridiagonal T from d and e.
+				tMat := zeros(n, n, n)
+				for i := 0; i < n; i++ {
+					tMat.Data[i*tMat.Stride+i] = d[i]
+				}
+				if uplo == blas.Upper {
+					for j := 1; j < n; j++ {
+						tMat.Data[(j-1)*tMat.Stride+j] = e[j-1]
+						tMat.Data[j*tMat.Stride+j-1] = e[j-1]
+					}
+				} else {
+					for j := 0; j < n-1; j++ {
+						tMat.Data[(j+1)*tMat.Stride+j] = e[j]
+						tMat.Data[j*tMat.Stride+j+1] = e[j]
+					}
+				}
+
+				// Compute Q^T * A * Q.
+				tmp := zeros(n, n, n)
+				blas64.Gemm(blas.Trans, blas.NoTrans, 1, q, aCopy, 0, tmp)
+				got := zeros(n, n, n)
+				blas64.Gemm(blas.NoTrans, blas.NoTrans, 1, tmp, q, 0, got)
+
+				// Compare with T.
+				if !equalApproxGeneral(got, tMat, tol) {
+					t.Errorf("%v: Q^T*A*Q != T", prefix)
 				}
-			if !floats.EqualApprox(tau, tau2, 1e-8) {
-				t.Errorf("Tau mismatch: %s", errStr)
 			}
 		}
 	}