NAME

       MAPGCI - Returns a set of points on the shortest great circle route between two user-
       specified points on the globe.

SYNOPSIS

       CALL MAPGCI(ALAT,ALON,BLAT,BLON,NOPI,RLTI,RLNI)

C-BINDING SYNOPSIS

       #include <ncarg/ncargC.h>

       void c_mapgci( float alat, float alon, float blat,
       float blon, int nopi, float *rlti, float *rlni)

DESCRIPTION

       ALAT and ALON
                   (input expressions, of type REAL) are the latitude and longitude of the point
                   at the beginning of a great circle route.

       BLAT and BLON
                   (input expressions, of type REAL) are the latitude and longitude of the point
                   at the end of a great circle route.

       NOPI        (an input expression, of type INTEGER) is the number of equally-spaced points
                   to be interpolated along the great circle route.

       RLTI and RLNI
                   (output arrays of type REAL, each dimensioned at least NOPI) are arrays
                   containing the latitudes and longitudes of points interpolated along the great
                   circle route.  Each lat/lon pair defines one of the points; they appear in
                   order of increasing distance along the great circle route.  The positions of
                   the first point and the last point are not returned in these arrays; only the
                   interpolated points are.

C-BINDING DESCRIPTION

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

USAGE

       The statement:

            CALL MAPGCI (ALAT,ALON,BLAT,BLON,NOPI,RLTI,RLNI)

       defines the positions of two points, A and B, on the globe and the number of equally-
       spaced points, NOPI, to be interpolated along the great circle route from A to B.  The
       latitudes and longitudes of the interpolated points are returned to the caller in the
       arrays RLTI and RLNI.  If the points A and B are exactly opposite one another on the
       globe, the code does not fail, but the direction of the great circle route will be
       somewhat unpredictable (since, in that case, there is more than one great circle route
       joining the two points).

EXAMPLES

       Use the ncargex command to see the following relevant example: cmpgci.

ACCESS

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

SEE ALSO

       Online: ezmap, ezmap_params, mapaci, mapbla, mapblm, mapdrw, mapeod, mapfst, mapgrd,
       mapgrm, mapgtc, mapgti, mapgtl, mapgtr, mapint, mapiq, mapiqa, mapiqd, mapiqm, mapit,
       mapita, mapitd, mapitm, maplbl, maplmb, maplot, mappos, maproj, maprs, maprst, mapsav,
       mapset, mapstc, mapsti, mapstl, mapstr, maptra, maptri, maptrn, mapusr, mapvec, mpchln,
       mpfnme, mpgetc, mpgeti, mpgetl, mpgetr, mpglty, mpiaty, mpifnb, mpilnb, mpiola, mpiosa,
       mpipai, mpipan, mpipar, mpisci, mplnam, mplndm, mplndr, mplnri, mpname, mprset, mpsetc,
       mpseti, mpsetl, mpsetr, supmap, supcon, ncarg_cbind

       Hardcopy: NCAR Graphics Contouring and Mapping Tutorial

COPYRIGHT

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