/// <summary>
/// Multiply a matrix transpose times a vector. If a rotation matrix is provided,
/// then this transforms the vector from one frame to another (inverse transform).
/// </summary>
public static Vec2 MulT(Mat22 A, Vec2 v)
{
return(new Vec2(Vec2.Dot(v, A.Col1), Vec2.Dot(v, A.Col2)));
}