code: function Matrix2D(a, b, c, d, tx, ty) {
  		this.setValues(a,b,c,d,tx,ty);
  
  	// public properties:
  		// assigned in the setValues method.
  		/**
  		 * Position (0, 0) in a 3x3 affine transformation matrix.
  		 * @property a
  		 * @type Number
  		 **/
  
  		/**
  		 * Position (0, 1) in a 3x3 affine transformation matrix.
  		 * @property b
  		 * @type Number
  		 **/
  
  		/**
  		 * Position (1, 0) in a 3x3 affine transformation matrix.
  		 * @property c
  		 * @type Number
  		 **/
  
  		/**
  		 * Position (1, 1) in a 3x3 affine transformation matrix.
  		 * @property d
  		 * @type Number
  		 **/
  
  		/**
  		 * Position (2, 0) in a 3x3 affine transformation matrix.
  		 * @property tx
  		 * @type Number
  		 **/
  
  		/**
  		 * Position (2, 1) in a 3x3 affine transformation matrix.
  		 * @property ty
  		 * @type Number
  		 **/
  	}
docs: constructor: 
  Represents an affine transformation matrix, and provides tools for constructing and concatenating matrices.
  
  This matrix can be visualized as:
  
  [ a  c  tx
  b  d  ty
  0  0  1  ]
  
  Note the locations of b and c.
  
  @class Matrix2D
  @param {Number} [a=1] Specifies the a property for the new matrix.
  @param {Number} [b=0] Specifies the b property for the new matrix.
  @param {Number} [c=0] Specifies the c property for the new matrix.
  @param {Number} [d=1] Specifies the d property for the new matrix.
  @param {Number} [tx=0] Specifies the tx property for the new matrix.
  @param {Number} [ty=0] Specifies the ty property for the new matrix.
  @constructor