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// Copyright ©2021 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/floats"
"gonum.org/v1/gonum/lapack"
)
type Dlangber interface {
Dlangb(norm lapack.MatrixNorm, m, n, kl, ku int, ab []float64, ldab int) float64
}
func DlangbTest(t *testing.T, impl Dlangber) {
rnd := rand.New(rand.NewSource(1))
for _, norm := range []lapack.MatrixNorm{lapack.MaxAbs, lapack.MaxRowSum, lapack.MaxColumnSum, lapack.Frobenius} {
t.Run(normToString(norm), func(t *testing.T) {
for _, n := range []int{0, 1, 2, 3, 4, 5, 10} {
for _, m := range []int{0, 1, 2, 3, 4, 5, 10} {
for _, kl := range []int{0, 1, 2, 3, 4, 5, 10} {
for _, ku := range []int{0, 1, 2, 3, 4, 5, 10} {
for _, ldab := range []int{kl + ku + 1, kl + ku + 1 + 7} {
dlangbTest(t, impl, rnd, norm, m, n, kl, ku, ldab)
}
}
}
}
}
})
}
}
func dlangbTest(t *testing.T, impl Dlangber, rnd *rand.Rand, norm lapack.MatrixNorm, m, n, kl, ku, ldab int) {
const tol = 1e-14
name := fmt.Sprintf("m=%v,n=%v,kl=%v,ku=%v,ldab=%v", m, n, kl, ku, ldab)
// Generate a random band matrix.
ab := randomSlice(m*ldab, rnd)
// Sometimes put a NaN into the matrix.
if m > 0 && n > 0 && rnd.Float64() < 0.5 {
i := rnd.Intn(m)
ab[i*ldab+kl] = math.NaN()
}
abCopy := make([]float64, len(ab))
copy(abCopy, ab)
// Deal with zero-sized matrices early.
if m == 0 || n == 0 {
got := impl.Dlangb(norm, m, n, kl, ku, nil, ldab)
if got != 0 {
t.Errorf("%v: unexpected result for zero-sized matrix with nil input", name)
}
got = impl.Dlangb(norm, m, n, kl, ku, ab, ldab)
if !floats.Same(ab, abCopy) {
t.Errorf("%v: unexpected modification in dl", name)
}
if got != 0 {
t.Errorf("%v: unexpected result for zero-sized matrix with non-nil input", name)
}
return
}
got := impl.Dlangb(norm, m, n, kl, ku, ab, ldab)
if !floats.Same(ab, abCopy) {
t.Errorf("%v: unexpected modification in ab", name)
}
// Generate a dense representation of the matrix and compute the wanted result.
a := zeros(m, n, n)
for i := 0; i < m; i++ {
for j := max(0, i-kl); j < min(i+ku+1, n); j++ {
a.Data[i*a.Stride+j] = ab[i*ldab+j-i+kl]
}
}
want := dlange(norm, a.Rows, a.Cols, a.Data, a.Stride)
if math.IsNaN(want) {
if !math.IsNaN(got) {
t.Errorf("%v: unexpected result with NaN element; got %v, want %v", name, got, want)
}
return
}
if math.IsNaN(got) {
t.Errorf("%v: unexpected NaN; want %v", name, want)
return
}
if norm == lapack.MaxAbs {
if got != want {
t.Errorf("%v: unexpected result; got %v, want %v", name, got, want)
}
return
}
diff := math.Abs(got - want)
if diff > tol {
t.Errorf("%v: unexpected result; got %v, want %v, diff=%v", name, got, want, diff)
}
}
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