1 // Copyright ©2016 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.
12 "golang.org/x/exp/rand"
15 type Dlanv2er interface {
16 Dlanv2(a, b, c, d float64) (aa, bb, cc, dd float64, rt1r, rt1i, rt2r, rt2i float64, cs, sn float64)
19 func Dlanv2Test(t *testing.T, impl Dlanv2er) {
20 rnd := rand.New(rand.NewSource(1))
21 for i := 0; i < 1000; i++ {
22 a := rnd.NormFloat64()
23 b := rnd.NormFloat64()
24 c := rnd.NormFloat64()
25 d := rnd.NormFloat64()
26 aa, bb, cc, dd, rt1r, rt1i, rt2r, rt2i, cs, sn := impl.Dlanv2(a, b, c, d)
28 mat := fmt.Sprintf("[%v %v; %v %v]", a, b, c, d)
30 if rt1i != 0 || rt2i != 0 {
31 t.Errorf("Unexpected complex eigenvalues for %v", mat)
35 t.Errorf("Diagonal elements not equal for %v: got [%v %v]", mat, aa, dd)
38 t.Errorf("Non-diagonal elements have the same sign for %v: got [%v %v]", mat, bb, cc)
40 im := math.Sqrt(-bb * cc)
41 if math.Abs(rt1i-im) > 1e-14 && math.Abs(rt1i+im) > 1e-14 {
42 t.Errorf("Unexpected imaginary part of eigenvalue for %v: got %v, want %v or %v", mat, rt1i, im, -im)
44 if math.Abs(rt2i-im) > 1e-14 && math.Abs(rt2i+im) > 1e-14 {
45 t.Errorf("Unexpected imaginary part of eigenvalue for %v: got %v, want %v or %v", mat, rt2i, im, -im)
49 if rt1r != aa && rt1r != dd {
50 t.Errorf("Unexpected real part of eigenvalue for %v: got %v, want %v or %v", mat, rt1r, aa, dd)
52 if rt2r != aa && rt2r != dd {
53 t.Errorf("Unexpected real part of eigenvalue for %v: got %v, want %v or %v", mat, rt2r, aa, dd)
55 if math.Abs(math.Hypot(cs, sn)-1) > 1e-14 {
56 t.Errorf("Unexpected unitary matrix for %v: got cs %v, sn %v", mat, cs, sn)
59 gota := cs*(aa*cs-bb*sn) - sn*(cc*cs-dd*sn)
60 gotb := cs*(aa*sn+bb*cs) - sn*(cc*sn+dd*cs)
61 gotc := sn*(aa*cs-bb*sn) + cs*(cc*cs-dd*sn)
62 gotd := sn*(aa*sn+bb*cs) + cs*(cc*sn+dd*cs)
63 if math.Abs(gota-a) > 1e-14 ||
64 math.Abs(gotb-b) > 1e-14 ||
65 math.Abs(gotc-c) > 1e-14 ||
66 math.Abs(gotd-d) > 1e-14 {
67 t.Errorf("Unexpected factorization: got [%v %v; %v %v], want [%v %v; %v %v]", gota, gotb, gotc, gotd, a, b, c, d)