struct grid_description
{
    int    num_rows ;
    int    num_cols ;
    int    num_vect_rows ;
    int    num_vect_cols ;
    double length ;           /*  distance to shift to the east  */
    double width ;           /*  distance to shift to the north  */
    double origin_x ;        /*  lower left point of grid  */
    double origin_y ;
    double angle ;
};