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// Copyright ©2020 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"
"math"
"testing"
"golang.org/x/exp/rand"
"gonum.org/v1/gonum/blas"
"gonum.org/v1/gonum/blas/blas64"
"gonum.org/v1/gonum/lapack"
)
type Dgtsver interface {
Dgtsv(n, nrhs int, dl, d, du []float64, b []float64, ldb int) (ok bool)
}
func DgtsvTest(t *testing.T, impl Dgtsver) {
rnd := rand.New(rand.NewSource(1))
for _, n := range []int{0, 1, 2, 3, 4, 5, 10, 25, 50} {
for _, nrhs := range []int{0, 1, 2, 3, 4, 10} {
for _, ldb := range []int{max(1, nrhs), nrhs + 3} {
dgtsvTest(t, impl, rnd, n, nrhs, ldb)
}
}
}
}
func dgtsvTest(t *testing.T, impl Dgtsver, rnd *rand.Rand, n, nrhs, ldb int) {
const (
tol = 1e-14
extra = 10
)
name := fmt.Sprintf("Case n=%d,nrhs=%d,ldb=%d", n, nrhs, ldb)
if n == 0 {
ok := impl.Dgtsv(n, nrhs, nil, nil, nil, nil, ldb)
if !ok {
t.Errorf("%v: unexpected failure for zero size matrix", name)
}
return
}
// Generate three random diagonals.
var (
d, dCopy []float64
dl, dlCopy []float64
du, duCopy []float64
)
d = randomSlice(n+1+extra, rnd)
dCopy = make([]float64, len(d))
copy(dCopy, d)
if n > 1 {
dl = randomSlice(n+extra, rnd)
dlCopy = make([]float64, len(dl))
copy(dlCopy, dl)
du = randomSlice(n+extra, rnd)
duCopy = make([]float64, len(du))
copy(duCopy, du)
}
b := randomGeneral(n, nrhs, ldb, rnd)
got := cloneGeneral(b)
ok := impl.Dgtsv(n, nrhs, dl, d, du, got.Data, got.Stride)
if !ok {
t.Fatalf("%v: unexpected failure in Dgtsv", name)
return
}
// Compute A*X - B.
dlagtm(blas.NoTrans, n, nrhs, 1, dlCopy, dCopy, duCopy, got.Data, got.Stride, -1, b.Data, b.Stride)
anorm := dlangt(lapack.MaxColumnSum, n, dlCopy, dCopy, duCopy)
bi := blas64.Implementation()
var resid float64
for j := 0; j < nrhs; j++ {
bnorm := bi.Dasum(n, b.Data[j:], b.Stride)
xnorm := bi.Dasum(n, got.Data[j:], got.Stride)
resid = math.Max(resid, bnorm/anorm/xnorm)
}
if resid > tol {
t.Errorf("%v: unexpected result; resid=%v,want<=%v", name, resid, tol)
}
}
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