TDPRPA - Given the parallelogram coordinates of a point, get the coordinates of its projection in the

       To  use TDPRPA or c_tdprpa, load the NCAR Graphics libraries ncarg, ncarg_gks, and ncarg_c, preferably in
       that order.

       The C-binding argument descriptions are the same as the FORTRAN argument descriptions.

       #include <ncarg/ncargC.h>

       void c_tdprpa(float xipa, float yipa, float *xi2d, float *yi2d)

       Copyright (C) 1987-2009
       University Corporation for Atmospheric Research
       The use of this Software is governed by a License Agreement.

UNIX                                                July 1997                                     TDPRPA(3NCARG)

       The arguments of TDPRPA are as follows:

       XIPA and YIPA
               (input  expressions of type REAL) - the parallelogram coordinates of a point.  (The parallelogram
               is as defined by a prior call to TDPARA.)

       XI2D and YI2D
               (output variables of type REAL) -  the  coordinates  of  the  projection  of  the  point  in  the
               projection plane.

       TDPRPA - Given the parallelogram coordinates of a point, get the coordinates of its projection in the
       projection plane.  This routine is essentially the inverse of the routine TDPRPI.

       Online: tdclrs, tdctri, tddtri, tdgeti, tdgetr, tdgrds, tdgrid, tdgtrs, tdinit, tditri,  tdlbla,  tdlbls,
       tdline,  tdlnpa,  tdmtri,  tdotri, tdpack, tdpack_params, tdpara, tdplch, tdprpi, tdprpt, tdseti, tdsetr,
       tdsort, tdstri, tdstrs

       CALL TDPRPA (XIPA, YIPA, XI2D, YI2D)