You can get access to matrix elements in a number of ways:
The code below shows the setElement function and the declaration for EMatrixIndex. Applying the matrix to a rational point (x, y, w) results in a rational point (x', y', w') using matrix multiplication:
setElement( EMatrixIndex index, GCoordinate& element );
EMatrixIndex{
kScaleX = 0, kSheary = 1, kPerspectiveX = 2,
kShearX = 3, kScaly = 4, kPerspectivey = 5,
kTranslateX = 6, kTranslatey = 7, kHomogeneous = 8
};