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74 lines
1.8 KiB
Go
74 lines
1.8 KiB
Go
// Copyright ©2016 The Gonum Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package testlapack
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import (
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"math"
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"testing"
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"golang.org/x/exp/rand"
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"gonum.org/v1/gonum/blas"
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"gonum.org/v1/gonum/blas/blas64"
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)
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type Dlacn2er interface {
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Dlacn2(n int, v, x []float64, isgn []int, est float64, kase int, isave *[3]int) (float64, int)
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}
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func Dlacn2Test(t *testing.T, impl Dlacn2er) {
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rnd := rand.New(rand.NewSource(1))
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for _, n := range []int{1, 2, 3, 4, 5, 7, 10, 15, 20, 100} {
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for cas := 0; cas < 10; cas++ {
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a := randomGeneral(n, n, n, rnd)
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// Compute the 1-norm of A explicitly.
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var norm1 float64
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for j := 0; j < n; j++ {
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var sum float64
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for i := 0; i < n; i++ {
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sum += math.Abs(a.Data[i*a.Stride+j])
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}
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if sum > norm1 {
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norm1 = sum
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}
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}
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// Compute the estimate of 1-norm using Dlanc2.
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x := make([]float64, n)
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work := make([]float64, n)
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v := make([]float64, n)
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isgn := make([]int, n)
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var (
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kase int
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isave [3]int
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got float64
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)
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loop:
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for {
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got, kase = impl.Dlacn2(n, v, x, isgn, got, kase, &isave)
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switch kase {
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default:
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panic("Dlacn2 returned invalid value of kase")
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case 0:
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break loop
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case 1:
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blas64.Gemv(blas.NoTrans, 1, a, blas64.Vector{Data: x, Inc: 1}, 0, blas64.Vector{Data: work, Inc: 1})
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copy(x, work)
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case 2:
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blas64.Gemv(blas.Trans, 1, a, blas64.Vector{Data: x, Inc: 1}, 0, blas64.Vector{Data: work, Inc: 1})
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copy(x, work)
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}
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}
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// Check that got is either accurate enough or a
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// lower estimate of the 1-norm of A.
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if math.Abs(got-norm1) > 1e-8 && got > norm1 {
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t.Errorf("Case n=%v: not lower estimate. 1-norm %v, estimate %v", n, norm1, got)
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}
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}
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}
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}
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