// Copyright ©2023 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/lapack"
)

type Dlanhser interface {
	Dlanhs(norm lapack.MatrixNorm, n int, a []float64, lda int, work []float64) (resultNorm float64)
}

func DlanhsTest(t *testing.T, impl Dlanhser) {
	const tol = 1e-8
	work := make([]float64, 9*9)
	rnd := rand.New(rand.NewSource(1))
	for _, n := range []int{1, 2, 4, 9} {
		for _, lda := range []int{n, n + 5} {
			a := randomHessenberg(n, lda, rnd)
			for _, norm := range []lapack.MatrixNorm{lapack.MaxAbs, lapack.MaxRowSum, lapack.MaxColumnSum, lapack.Frobenius} {
				expect := dlange(norm, a.Rows, a.Cols, a.Data, a.Stride)
				got := impl.Dlanhs(norm, a.Rows, a.Data, lda, work)
				if math.Abs(expect-got)/expect > tol {
					t.Errorf("Case n=%v,lda=%v,norm=%v: unexpected result. Want %v, got %v.", n, lda, normToString(norm), expect, got)
				}
			}

		}
	}
}