This .NET class wraps the AcGeMatrix2d ObjectARX class. 

Class Matrix2d represents an affine transformation of 3D space, including translation. Each matrix M has the form: 

a00 a01 t0
a10 a11 t1
0    0    1

where the matrix A: 

a00 a01
a10 a11

is called the linear part of M. 

Column T: 

t0
t1

is called a translational part of M. 

To get Point2d point transformed by corresponding transformation, one has to take the product M x P of the matrix M and point-column P = ( pnt.x, pnt.y, 1.0) to the power of T. To get Vector2d vector transformed by corresponding transformation, one has to take the product M x V of the matrix M and vector-column V = ( vec.x, vec.y, 0.0) to the power of T. 

Every matrix M is associated with a coordinate system. This coordinate system has the origin (t₀, t₁) and vectors (a₀₀, a₁₀) and (a₀₁, a₁₁) as axes. Matrix M maps the standard coordinate system to the coordinate system with the origin (0, 0) and axes (1, 0) and (0, 1).

Public Structure Matrix2d
Inherits IFormattable
End Structure

public struct Matrix2d : IFormattable {
}