mirror of
https://github.com/gonum/gonum.git
synced 2025-10-31 02:26:59 +08:00
65 lines
1.5 KiB
Go
65 lines
1.5 KiB
Go
// Copyright ©2019 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"
|
|
)
|
|
|
|
type Dlassqer interface {
|
|
Dlassq(n int, x []float64, incx int, scale, ssq float64) (float64, float64)
|
|
}
|
|
|
|
func DlassqTest(t *testing.T, impl Dlassqer) {
|
|
const tol = 1e-14
|
|
|
|
rnd := rand.New(rand.NewSource(1))
|
|
for _, n := range []int{0, 1, 2, 3, 4, 5, 10} {
|
|
for _, incx := range []int{1, 3} {
|
|
name := fmt.Sprintf("n=%v,incx=%v", n, incx)
|
|
|
|
// Allocate a slice of minimum length and fill it with
|
|
// random numbers.
|
|
x := make([]float64, max(0, 1+(n-1)*incx))
|
|
for i := range x {
|
|
x[i] = rnd.Float64()
|
|
}
|
|
|
|
// Fill the referenced elements of x and compute the
|
|
// expected result in a non-sophisticated way.
|
|
scale := rnd.Float64()
|
|
ssq := rnd.Float64()
|
|
want := scale * scale * ssq
|
|
for i := 0; i < n; i++ {
|
|
xi := rnd.NormFloat64()
|
|
x[i*incx] = xi
|
|
want += xi * xi
|
|
}
|
|
|
|
xCopy := make([]float64, len(x))
|
|
copy(xCopy, x)
|
|
|
|
// Update scale and ssq so that
|
|
// scale_out^2 * ssq_out = x[0]^2 + ... + x[n-1]^2 + scale_in^2*ssq_in
|
|
scale, ssq = impl.Dlassq(n, x, incx, scale, ssq)
|
|
if !floats.Equal(x, xCopy) {
|
|
t.Fatalf("%v: unexpected modification of x", name)
|
|
}
|
|
|
|
// Check the result.
|
|
got := scale * scale * ssq
|
|
if math.Abs(got-want) >= tol {
|
|
t.Errorf("%v: unexpected result; got %v, want %v", name, got, want)
|
|
}
|
|
}
|
|
}
|
|
}
|