gonum.org/v1/gonum@v0.15.1-0.20240517103525-f853624cb1bb/lapack/testlapack/dlanhs.go (about)

     1  // Copyright ©2023 The Gonum Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package testlapack
     6  
     7  import (
     8  	"math"
     9  	"testing"
    10  
    11  	"golang.org/x/exp/rand"
    12  
    13  	"gonum.org/v1/gonum/lapack"
    14  )
    15  
    16  type Dlanhser interface {
    17  	Dlanhs(norm lapack.MatrixNorm, n int, a []float64, lda int, work []float64) float64
    18  }
    19  
    20  func DlanhsTest(t *testing.T, impl Dlanhser) {
    21  	const tol = 1e-15
    22  	rnd := rand.New(rand.NewSource(1))
    23  	for _, n := range []int{0, 1, 2, 4, 9} {
    24  		for _, lda := range []int{max(1, n), n + 5} {
    25  			a := randomGeneral(n, n, lda, rnd)
    26  			for _, norm := range []lapack.MatrixNorm{lapack.MaxAbs, lapack.MaxRowSum, lapack.MaxColumnSum, lapack.Frobenius} {
    27  				var work []float64
    28  				if norm == lapack.MaxColumnSum {
    29  					work = nanSlice(n)
    30  				}
    31  
    32  				got := impl.Dlanhs(norm, a.Rows, a.Data, lda, work)
    33  
    34  				// Zero out A below the first subdiagonal.
    35  				for i := 2; i < n; i++ {
    36  					for j := 0; j < max(0, i-1); j++ {
    37  						a.Data[i*a.Stride+j] = 0
    38  					}
    39  				}
    40  				want := dlange(norm, a.Rows, a.Cols, a.Data, a.Stride)
    41  
    42  				if math.Abs(want-got) > tol*want {
    43  					t.Errorf("Case n=%v,lda=%v,norm=%v: unexpected result. Want %v, got %v.", n, lda, normToString(norm), want, got)
    44  				}
    45  			}
    46  		}
    47  	}
    48  }