m.gc2ll <main>	      GRASS Reference Manual	   <main> m.gc2ll



NAME
     m.gc2ll - Converts geocentric to geographic coordinates.
     (GRASS Data Import/Processing Program)

SYNOPSIS
     m.gc2ll x=# y=# z=# s=spheroid

DESCRIPTION
     m.gc2ll returns geographic coordinates for geocentric ones
     supplied by the user.  It performs the reverse operation of
     the GRASS program m.ll2gc.	 The x, y and z values are the
     three dimensions needed to locate a point in three-
     dimensional space.	 The values that are printed include the
     latitude, the longitude and the height above (or distance
     below) the spheroid.

     The list of spheroids available is somewhat dynamic.  It may
     not contain exactly the ones listed below.	 To determine the
     current list of possible spheroids, simply type in:

	  m.gc2ll x=0 y=0 z=0 s=help

     A list of available spheroids will be printed on the screen.
     If the spheroid desired is not on the list, the values for
     the semi-major axis and the eccentricity squared for the
     spheroid may be entered in place of a spheroid name in the
     following format:

	  s=a=semi-major_axis,e=eccentricity_squared

     SOME POSSIBLE SPHEROIDS
     (The on-line listing includes only the spheroid names)
       Spheroid	   | Commonly used for: | Semi-major axis | Eccentricity sqrd
     --------------+--------------------+-----------------+-------------------
     australian	   | Australia		| 6378160.0	  | 0.0066945419
     bessel	   | Japan		| 6377739.155	  | 0.0066743722
     clark66	   | N. America		| 6378206.4	  | 0.006768658
     clark80	   | France, Africa	| 6378249.145	  | 0.0068035113
     everest	   | India, Burma	| 6377276.345	  | 0.0066378466
     international | Europe		| 6378388.0	  | 0.00672267
     wgs72	   | worldwide coverage | 6378135.0	  | 0.006694317778

EXAMPLE
     m.gc2ll x=0.0 y=0.0 z=6356750.520017 s=wgs72

     Results:
	 lat=90N
	 lon=90W
	 h=0.0000

NOTES
     For a brief discussion of spheroids see m.ll2u.



GRASS 5.0beta6	      GRASS Development Team			1






m.gc2ll <main>	      GRASS Reference Manual	   <main> m.gc2ll



     For a brief discussion of geocentric coordinates see
     m.ll2gc.

     This is an experimental program.  It is part of an initial
     effort to incorporate geographic coordinates into GRASS.

SEE ALSO
     m.datum.shift, m.ll2gc, m.ll2u, m.u2ll

AUTHOR
     Michael Shapiro, U.S. Army Construction Engineering Research
     Laboratory











































2		      GRASS Development Team	   GRASS 5.0beta6