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// Copyright ©2016 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"
)
type Dlae2er interface {
Dlae2(a, b, c float64) (rt1, rt2 float64)
}
func Dlae2Test(t *testing.T, impl Dlae2er) {
for _, test := range []struct {
a, b, c float64
}{
{-10, 5, 3},
{3, 5, -10},
{0, 3, 0},
{1, 3, 1},
{1, -3, 1},
{5, 0, 3},
{3, 0, -5},
{1, 3, 1.02},
{1.02, 3, 1},
{1, -3, -9},
} {
a := test.a
b := test.b
c := test.c
rt1, rt2 := impl.Dlae2(a, b, c)
errStr := fmt.Sprintf("a = %v, b = %v, c = %v", a, b, c)
// Check if rt1 and rt2 are eigenvalues by checking if det(a - λI) = 0
a1 := a - rt1
c1 := c - rt1
det := a1*c1 - b*b
if math.Abs(det) > 1e-10 {
t.Errorf("First eigenvalue mismatch. %s. Det = %v", errStr, det)
}
a2 := a - rt2
c2 := c - rt2
det = a2*c2 - b*b
if math.Abs(det) > 1e-10 {
t.Errorf("Second eigenvalue mismatch. %s. Det = %v", errStr, det)
}
}
}
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