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// Copyright ©2017 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 (
"testing"
"golang.org/x/exp/rand"
"gonum.org/v1/gonum/blas/blas64"
)
func TestDlagsy(t *testing.T) {
const tol = 1e-14
rnd := rand.New(rand.NewSource(1))
for _, n := range []int{0, 1, 2, 3, 4, 5, 10, 50} {
for _, lda := range []int{0, 2*n + 1} {
if lda == 0 {
lda = max(1, n)
}
// D is the identity matrix I.
d := make([]float64, n)
for i := range d {
d[i] = 1
}
// Allocate an n×n symmetric matrix A and fill it with NaNs.
a := nanSlice(n * lda)
work := make([]float64, 2*n)
// Compute A = U * D * Uᵀ where U is a random orthogonal matrix.
Dlagsy(n, 0, d, a, lda, rnd, work)
// A should be the identity matrix because
// A = U * D * Uᵀ = U * I * Uᵀ = U * Uᵀ = I.
dist := distFromIdentity(n, a, lda)
if dist > tol {
t.Errorf("Case n=%v,lda=%v: |A-I|=%v is too large", n, lda, dist)
}
}
}
}
func TestDlagge(t *testing.T) {
const tol = 1e-14
rnd := rand.New(rand.NewSource(1))
for _, n := range []int{0, 1, 2, 3, 4, 5, 10, 50} {
for _, lda := range []int{0, 2*n + 1} {
if lda == 0 {
lda = max(1, n)
}
d := make([]float64, n)
for i := range d {
d[i] = 1
}
a := blas64.General{
Rows: n,
Cols: n,
Stride: lda,
Data: nanSlice(n * lda),
}
work := make([]float64, a.Rows+a.Cols)
Dlagge(a.Rows, a.Cols, 0, 0, d, a.Data, a.Stride, rnd, work)
if resid := residualOrthogonal(a, false); resid > tol {
t.Errorf("Case n=%v,lda=%v: unexpected result", n, lda)
}
}
}
}
func TestRandomOrthogonal(t *testing.T) {
const tol = 1e-14
rnd := rand.New(rand.NewSource(1))
for n := 1; n <= 20; n++ {
q := randomOrthogonal(n, rnd)
if resid := residualOrthogonal(q, false); resid > tol {
t.Errorf("Case n=%v: Q not orthogonal; resid=%v, want<=%v", n, resid, tol)
}
}
}
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