plucky (3) nggcog.3NCARG.gz

NAME

       NGGCOG - Returns the latitudes and longitudes of a set of points approximating a circle at a given point
       on the surface of the globe.

SYNOPSIS

       CALL NGGCOG (CLAT,CLON,CRAD,ALAT,ALON,NPTS)

C-BINDING SYNOPSIS

       #include <ncarg/ncargC.h>

       void c_nggcog(float clat, float clon, float crad, float *alat,
       float *alon, int npts)

DESCRIPTION

       CLAT        (an input expression of type REAL) is the latitude, in degrees, of a point on the globe
                   defining the center of the circle.

       CLON        (an input expression of type REAL) is the longitude, in degrees, of a point on the globe
                   defining the center of the circle.

       CRAD        (an input expression of type REAL) specifies the radius of the circle.  This is given as a
                   great-circle distance, in degrees.

       ALAT        (an output array, of type REAL, dimensioned NPTS) is an array in which the latitudes of
                   points on the circle are to be returned.

       ALON        (an output array, of type REAL, dimensioned NPTS) is an array in which the longitudes of
                   points on the circle are to be returned.

       NPTS        (an input expression, of type INTEGER) is the desired number of points to be used to
                   represent the circle.  Its value determines how accurately the circle will be represented.

C-BINDING DESCRIPTION

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

USAGE

       Let C represent (CLAT,CLON) and let O represent the center of the globe.  The circle is the set of all
       points P on the globe such that the angle POC is of the size specified by CRAD.

       SIN and COS are used to generate points representing a circle having the desired radius and centered at
       the North Pole.  These points are then subjected to two rotations - one that brings the circle down to
       the desired latitude, and another that carries it to the desired longitude.

EXAMPLES

       Use the ncargex command to see the following relevant example: cpex10.

ACCESS

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

MESSAGES

       None.

SEE ALSO

       Online: nggsog(3NCARG), ngritd(3NCARG).

COPYRIGHT

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