Files
gonum/lapack/testlapack/dlapmr.go
2025-02-01 22:18:04 +10:30

86 lines
2.1 KiB
Go

// Copyright ©2022 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/rand/v2"
"testing"
"gonum.org/v1/gonum/blas"
"gonum.org/v1/gonum/blas/blas64"
)
type Dlapmrer interface {
Dlapmr(forwrd bool, m, n int, x []float64, ldx int, k []int)
}
func DlapmrTest(t *testing.T, impl Dlapmrer) {
rnd := rand.New(rand.NewPCG(1, 1))
for _, fwd := range []bool{true, false} {
for _, m := range []int{0, 1, 2, 3, 4, 5, 10} {
for _, n := range []int{0, 1, 4} {
for _, ldx := range []int{max(1, n), n + 3} {
dlapmrTest(t, impl, rnd, fwd, m, n, ldx)
}
}
}
}
}
func dlapmrTest(t *testing.T, impl Dlapmrer, rnd *rand.Rand, fwd bool, m, n, ldx int) {
name := fmt.Sprintf("forwrd=%v,m=%d,n=%d,ldx=%d", fwd, m, n, ldx)
bi := blas64.Implementation()
// Generate a random permutation and simultaneously apply it to the rows of the identity matrix.
k := make([]int, m)
for i := range k {
k[i] = i
}
p := eye(m, m)
for i := 0; i < m-1; i++ {
j := i + rnd.IntN(m-i)
k[i], k[j] = k[j], k[i]
bi.Dswap(m, p.Data[i*p.Stride:], 1, p.Data[j*p.Stride:], 1)
}
kCopy := make([]int, len(k))
copy(kCopy, k)
// Generate a random matrix X.
x := randomGeneral(m, n, ldx, rnd)
// Applying the permutation k with Dlapmr is the same as multiplying X with P or Pᵀ from the left:
// - forward permutation: P * X
// - backward permutation: Pᵀ* X
trans := blas.NoTrans
if !fwd {
trans = blas.Trans
}
want := zeros(m, n, n)
bi.Dgemm(trans, blas.NoTrans, m, n, m, 1, p.Data, p.Stride, x.Data, x.Stride, 0, want.Data, want.Stride)
// Apply the permutation in k to X.
impl.Dlapmr(fwd, m, n, x.Data, x.Stride, k)
got := x
// Check that k hasn't been modified in Dlapmr.
var kmod bool
for i, ki := range k {
if ki != kCopy[i] {
kmod = true
break
}
}
if kmod {
t.Errorf("%s: unexpected modification of k", name)
}
// Check that Dlapmr yields the same result as multiplication with P.
if !equalGeneral(got, want) {
t.Errorf("%s: unexpected result", name)
}
}