From f1575d06758e29f1d69c9dab403f2b9d7accd36e Mon Sep 17 00:00:00 2001
From: Vladimir Chalupecky <vladimir.chalupecky@gmail.com>
Date: Mon, 25 Apr 2016 20:42:12 +0900
Subject: [PATCH] native: add test for Dlaqr1

---
 native/lapack_test.go |  4 ++
 testlapack/dlaqr1.go  | 91 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 95 insertions(+)
 create mode 100644 testlapack/dlaqr1.go

diff --git a/native/lapack_test.go b/native/lapack_test.go
index b147132d..0e021839 100644
--- a/native/lapack_test.go
+++ b/native/lapack_test.go
@@ -112,6 +112,10 @@ func TestDlanv2(t *testing.T) {
 	testlapack.Dlanv2Test(t, impl)
 }
 
+func TestDlaqr1(t *testing.T) {
+	testlapack.Dlaqr1Test(t, impl)
+}
+
 func TestDlarfb(t *testing.T) {
 	testlapack.DlarfbTest(t, impl)
 }
diff --git a/testlapack/dlaqr1.go b/testlapack/dlaqr1.go
new file mode 100644
index 00000000..63eaa4c0
--- /dev/null
+++ b/testlapack/dlaqr1.go
@@ -0,0 +1,91 @@
+// 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 (
+	"math"
+	"math/rand"
+	"testing"
+
+	"github.com/gonum/floats"
+)
+
+type Dlaqr1er interface {
+	Dlaqr1(n int, h []float64, ldh int, sr1, si1, sr2, si2 float64, v []float64)
+}
+
+func Dlaqr1Test(t *testing.T, impl Dlaqr1er) {
+	rnd := rand.New(rand.NewSource(1))
+
+	for _, n := range []int{2, 3} {
+		for _, ldh := range []int{n, n + 1, n + 10} {
+			for _, cas := range []int{1, 2} {
+				for k := 0; k < 100; k++ {
+					v := make([]float64, n)
+					for i := range v {
+						v[i] = math.NaN()
+					}
+					h := make([]float64, n*(n-1)*ldh)
+					for i := range h {
+						h[i] = math.NaN()
+					}
+					for i := 0; i < n; i++ {
+						for j := 0; j < n; j++ {
+							h[i*ldh+j] = rnd.NormFloat64()
+						}
+					}
+					var sr1, sr2, si1, si2 float64
+					if cas == 1 {
+						sr1 = rnd.NormFloat64()
+						sr2 = sr1
+						si1 = rnd.NormFloat64()
+						si2 = -si1
+					} else {
+						sr1 = rnd.NormFloat64()
+						sr2 = rnd.NormFloat64()
+						si1 = 0
+						si2 = 0
+					}
+					impl.Dlaqr1(n, h, ldh, sr1, si1, sr2, si2, v)
+
+					// Matrix H - s1*I.
+					h1 := make([]complex128, n*n)
+					for i := 0; i < n; i++ {
+						for j := 0; j < n; j++ {
+							h1[i*n+j] = complex(h[i*ldh+j], 0)
+							if i == j {
+								h1[i*n+j] -= complex(sr1, si1)
+							}
+						}
+					}
+					// First column of H - s2*I.
+					h2 := make([]complex128, n)
+					for i := 0; i < n; i++ {
+						h2[i] = complex(h[i*ldh], 0)
+					}
+					h2[0] -= complex(sr2, si2)
+
+					wantv := make([]float64, n)
+					// Multiply (H-s1*I)*(H-s2*I) to get a tentative
+					// wantv.
+					for i := 0; i < n; i++ {
+						for j := 0; j < n; j++ {
+							wantv[i] += real(h1[i*n+j] * h2[j])
+						}
+					}
+					// Get the unknown scale.
+					scale := v[0] / wantv[0]
+					// Compute the actual wantv.
+					floats.Scale(scale, wantv)
+
+					// The scale must be the same for all elements.
+					if floats.Distance(wantv, v, math.Inf(1)) > 1e-13 {
+						t.Errorf("n = %v, ldh = %v, case = %v: Unexpected value of v: got %v, want %v", n, ldh, cas, v, wantv)
+					}
+				}
+			}
+		}
+	}
+}