public void SubtractMatricesTest()
{
Matrix3x3 expectedResult = new Matrix3x3();
expectedResult.V00 = -1;
expectedResult.V01 = 1;
expectedResult.V02 = 0;
expectedResult.V10 = 2;
expectedResult.V11 = -1;
expectedResult.V12 = -1;
expectedResult.V20 = -2;
expectedResult.V21 = 1;
expectedResult.V22 = 1;
Matrix3x3 result = a1 - a2;
Assert.AreEqual(true, ApproximateEquals(result, expectedResult));
}