mat64: comment out failing clever case and note succeeding clever case

mat64/dense_test.go

@@ -1646,6 +1646,11 @@ func TestInverse(t *testing.T) {
 			}).T(),
 			tol: 1e-14,
 		},
+
+		// This case does not fail, but we do not guarantee that. The success
+		// is because the receiver and the input are aligned in the call to
+		// inverse. If there was a misalignment, the result would likely be
+		// incorrect and no shadowing panic would occur.
 		{
 			a: asBasicMatrix(NewDense(3, 3, []float64{
 				8, 1, 6,
@@ -1659,19 +1664,25 @@ func TestInverse(t *testing.T) {
 			}),
 			tol: 1e-14,
 		},
-		{
-			a: asBasicMatrix(NewDense(3, 3, []float64{
-				8, 1, 6,
-				3, 5, 7,
-				4, 9, 2,
-			})).T(),
-			want: NewDense(3, 3, []float64{
-				0.147222222222222, -0.144444444444444, 0.063888888888889,
-				-0.061111111111111, 0.022222222222222, 0.105555555555556,
-				-0.019444444444444, 0.188888888888889, -0.102777777777778,
-			}).T(),
-			tol: 1e-14,
-		},
+
+		// The following test will fail since it does not obey the shadowing
+		// rules. The basicMatrix type allows shadowing of the input data
+		// without providing the Raw mathod required for detection of shadowing.
+		//
+		// {
+		// 	a: asBasicMatrix(NewDense(3, 3, []float64{
+		// 		8, 1, 6,
+		// 		3, 5, 7,
+		// 		4, 9, 2,
+		// 	})).T(),
+		// 	want: NewDense(3, 3, []float64{
+		// 		0.147222222222222, -0.144444444444444, 0.063888888888889,
+		// 		-0.061111111111111, 0.022222222222222, 0.105555555555556,
+		// 		-0.019444444444444, 0.188888888888889, -0.102777777777778,
+		// 	}).T(),
+		// 	tol: 1e-14,
+		// },
+
 		{
 			a: NewDense(4, 4, []float64{
 				5, 2, 8, 7,