%                          wgs72con.m
%  Scope:   This MATLAB macro sets the World Geodetic System 1972 (WGS-72)
%           most used constants as global variables.
%  Usage:   wgs72con
%  Description of global parameters:
%           a_smaxis  -  output, WGS-72 earth semi-major axis in meters
%           b_smaxis  -  output, WGS-72 earth semi-minor axis in meters
%           eccentr   -  output, WGS-72 earth eccentricity 
%           eccentr2  -  output, WGS-72 earth eccentricity squared
%           flatness  -  output, WGS-72 flatness (ellipticity)
%           gravpar   -  output, WGS-72 gravity parameter in meters**3/sec**2
%                        earth's gravitational constant (mass of earth
%                        including earth's atmosphere)
%           rot_rate  -  output, WGS-72 earth rotation rate in radians/second
%           c_speed   -  output, speed of light in vacuum in meters/second
%           ucgrav    -  output, universal constant of gravity (G) in 
%                        meters**3/sec**2/Kg     
%           mearth    -  output, mass of earth (including the atmosphere) (M)
%                        in Kg       
%           g0        -  output, ellipsoidal equatorial gravity in meters/sec**2
%  Last update: 10/13/97
%  Copyright (C) 1996-97 by LL Consulting. All Rights Reserved.

global  a_smaxis b_smaxis eccentr eccentr2 flatness gravpar rot_rate c_speed
global  ucgrav mearth g0

%  Initialize the constants

a_smaxis = 6378135.; 
b_smaxis = 6356750.499955;
eccentr  = 0.08181884897576;
eccentr2 = 0.00669432404772;     %  eccentr2 = flatness * (2. - flatness)
flatness = 0.00335278259944;     %  1. / 298.2597202 = 1 - b_smaxis/a_smaxis

gravpar  = 3.986008e+14;
rot_rate = 7.292115147e-5; 
c_speed  = 2.99792458e+8;
ucgrav   = 6.673e-11;
mearth   = 5.9733328e+24;
g0       = 9.7803327;