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// Copyright ©2015 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 (
"math"
"testing"
"golang.org/x/exp/rand"
"gonum.org/v1/gonum/blas/blas64"
"gonum.org/v1/gonum/lapack"
)
type Dlanger interface {
Dlange(norm lapack.MatrixNorm, m, n int, a []float64, lda int, work []float64) float64
}
func DlangeTest(t *testing.T, impl Dlanger) {
rnd := rand.New(rand.NewSource(1))
for _, test := range []struct {
m, n, lda int
}{
{4, 3, 0},
{3, 4, 0},
{4, 3, 100},
{3, 4, 100},
} {
m := test.m
n := test.n
lda := test.lda
if lda == 0 {
lda = n
}
// Allocate m×n matrix A and fill it with random numbers from [-0.5, 0.5).
a := make([]float64, m*lda)
for i := range a {
a[i] = rnd.Float64() - 0.5
}
// Store a copy of A for later comparison.
aCopy := make([]float64, len(a))
copy(aCopy, a)
// Allocate workspace slice.
work := make([]float64, n)
for i := range work {
work[i] = rnd.Float64()
}
// Test various norms by comparing the result from Dlange with
// explicit calculation.
// Test MaxAbs norm.
norm := impl.Dlange(lapack.MaxAbs, m, n, a, lda, work)
var ans float64
for i := 0; i < m; i++ {
idx := blas64.Iamax(blas64.Vector{N: n, Inc: 1, Data: aCopy[i*lda:]})
ans = math.Max(ans, math.Abs(a[i*lda+idx]))
}
// Should be strictly equal because there is no floating point summation error.
if ans != norm {
t.Errorf("MaxAbs mismatch. Want %v, got %v.", ans, norm)
}
// Test MaxColumnSum norm.
norm = impl.Dlange(lapack.MaxColumnSum, m, n, a, lda, work)
ans = 0
for i := 0; i < n; i++ {
sum := blas64.Asum(blas64.Vector{N: m, Inc: lda, Data: aCopy[i:]})
ans = math.Max(ans, sum)
}
if math.Abs(norm-ans) > 1e-14 {
t.Errorf("MaxColumnSum mismatch. Want %v, got %v.", ans, norm)
}
// Test MaxRowSum norm.
norm = impl.Dlange(lapack.MaxRowSum, m, n, a, lda, work)
ans = 0
for i := 0; i < m; i++ {
sum := blas64.Asum(blas64.Vector{N: n, Inc: 1, Data: aCopy[i*lda:]})
ans = math.Max(ans, sum)
}
if math.Abs(norm-ans) > 1e-14 {
t.Errorf("MaxRowSum mismatch. Want %v, got %v.", ans, norm)
}
// Test Frobenius norm.
norm = impl.Dlange(lapack.Frobenius, m, n, a, lda, work)
ans = 0
for i := 0; i < m; i++ {
sum := blas64.Nrm2(blas64.Vector{N: n, Inc: 1, Data: aCopy[i*lda:]})
ans += sum * sum
}
ans = math.Sqrt(ans)
if math.Abs(norm-ans) > 1e-14 {
t.Errorf("Frobenius norm mismatch. Want %v, got %v.", ans, norm)
}
}
}
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