lapack/testlapack: add test for randomOrthogonal

... and remove the orthogonality assertion in randomOrthogonal.

lapack/testlapack/matgen.go

@@ -675,9 +675,6 @@ func randomOrthogonal(n int, rnd *rand.Rand) blas64.General {
 		// Compute Q * H_j and store the result into Q.
 		applyReflector(q, q, v)
 	}
-	if !isOrthogonal(q) {
-		panic("Q not orthogonal")
-	}
 	return q
 }
 

lapack/testlapack/matgen_test.go

@@ -89,3 +89,13 @@ func TestDlagge(t *testing.T) {
 	}
 
 }
+
+func TestRandomOrthogonal(t *testing.T) {
+	rnd := rand.New(rand.NewSource(1))
+	for n := 1; n <= 20; n++ {
+		q := randomOrthogonal(n, rnd)
+		if !isOrthogonal(q) {
+			t.Errorf("Case n=%v: Q not orthogonal", n)
+		}
+	}
+}