public Vector4 GetColumn(int index)
{
if ((index < 0) || (index > 3))
throw new ArgumentException("Invalid column index was specified.", "index");
return (index == 0) ? new Vector4(V00, V10, V20, V30) :
(index == 1) ? new Vector4(V01, V11, V21, V31) :
(index == 2) ? new Vector4(V02, V12, V22, V32) : new Vector4(V03, V13, V23, V33);
}