public Vec2 Clone()
{
return new Vec2(X, Y);
}
/// <summary>
/// Create a matrix with given vectors as columns.
/// </summary>
/// <param name="c1">Column 1 of matrix</param>
/// <param name="c2">Column 2 of matrix</param>
public Mat22(Vec2 c1, Vec2 c2)
{
Ex = c1.Clone();
Ey = c2.Clone();
}