func (self *Matrix) Multiply(a, b Matrix) {
C.cairo_matrix_multiply(self.cairo_matrix_t(), a.cairo_matrix_t(), b.cairo_matrix_t())
}
//Mul multiples m by n and returns the new result r, such that r = m*n.
//
//Originally cairo_matrix_multiply.
func (m Matrix) Mul(n Matrix) Matrix {
var r Matrix
C.cairo_matrix_multiply(&r.m, &m.m, &n.m)
return r
}