1NGGSOG(3NCARG)                   NCAR GRAPHICS                  NGGSOG(3NCARG)
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NAME

6       NGGSOG - Returns the latitudes and longitudes of six points defining a
7       five-pointed star at a given point on the surface of the globe.
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SYNOPSIS

10       CALL NGGSOG (SLAT,SLON,SRAD,ALAT,ALON)
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C-BINDING SYNOPSIS

13       #include <ncarg/ncargC.h>
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15       void c_nggsog(float slat, float slon, float srad, float *alat,
16       float *alon)
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DESCRIPTION

19       SLAT        (an input expression of type REAL) is the latitude, in
20                   degrees, of a point on the globe defining the center of the
21                   star.
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23       SLON        (an input expression of type REAL) is the longitude, in
24                   degrees, of a point on the globe defining the center of the
25                   star.
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27       SRAD        (an input expression of type REAL) specifies the great-
28                   circle distance, in degrees, from the center of the star to
29                   the end of one of its points.
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31       ALAT        (an output array, of type REAL, dimensioned 6) is an array
32                   in which the latitudes of points on the star are to be
33                   returned.
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35       ALON        (an output array, of type REAL, dimensioned 6) is an array
36                   in which the longitudes of points on the star are to be
37                   returned.
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C-BINDING DESCRIPTION

40       The C binding argument descriptions are the same as the FORTRAN
41       argument descriptions.
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USAGE

44       Let C represent (CLAT,CLON), let O represent the center of the globe,
45       and let P represent the end of one point of the star.  Then, the angle
46       POC has the magnitude specified by SRAD.
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48       SIN, COS, and TAN are used to generate points representing a star
49       having the desired radius and centered at the the point with latitude 0
50       and longitude 0.  These points are then subjected to two rotations -
51       one that brings the star up to the desired latitude, and another that
52       carries it to the desired longitude.
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54       NGGSOG is intended to be used for relatively small stars marking points
55       of interest on the surface of the globe; using SRAD = 90 degrees is
56       guaranteed to get you into trouble and SRAD < 10 degrees is
57       recommended.
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EXAMPLES

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

63       To use NGGSOG or c_nggsog, load the NCAR Graphics libraries ncarg,
64       ncarg_gks, and ncarg_c, preferably in that order.
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MESSAGES

67       None.
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SEE ALSO

70       Online: nggcog(3NCARG), ngritd(3NCARG).
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73       Copyright (C) 1987-2009
74       University Corporation for Atmospheric Research
75       The use of this Software is governed by a License Agreement.
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79UNIX                              March 1993                    NGGSOG(3NCARG)
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