(self)
return self[1, 1]
The D parameter of the Matrix.

        Examples
        ========

        >>> from sympy.physics.gaussopt import RayTransferMatrix
        >>> mat = RayTransferMatrix(1, 2, 3, 4)
        >>> mat.D
        4
The D parameter of the Matrix.
The D parameter of the Matrix .
def D(self):
        """
        The D parameter of the Matrix.

        Examples
        ========

        >>> from sympy.physics.gaussopt import RayTransferMatrix
        >>> mat = RayTransferMatrix(1, 2, 3, 4)
        >>> mat.D
        4
        """
        return self[1, 1]
def D ( self ) : return self [ 1 , 1 ]