latlon2xyz.m

JLAB is a set of Matlab functions I have written or co-written over the past fifteen years for the p

function[x,y,z]=latlon2xyz(lat,lon,R)
%LATLON2XYZ  Convert latitude and longitude into Cartesian coordinates.
%
%   [X,Y,Z]=LATLON2XYZ(LAT,LON) converts latitude and longitude of 
%   a position on the surface of a sphere into Cartesian coordinates.  
%
%   LAT and LON are in degrees and X, Y, and Z are in kilometers.
%
%   The Cartesian coordinate system is a right-handed system whose
%   origin lies at the center of the sphere.  It is oriented with the 
%   Z-axis passing though the poles and the X-axis passing through
%   the point LAT=0, LON=0.  
%
%   By default, the radius of the sphere is taken as RADEARTH.
%   LATLON2XYZ(LAT,LON,R) uses a sphere of radius R, in kilometers,
%   instead.
%
%   See also XYZ2LATLON.
%   __________________________________________________________________
%   This is part of JLAB --- type 'help jlab' for more information
%   (C) 2006 J.M. Lilly --- type 'help jlab_license' for details
 
if strcmp(lat, '--t')
    latlon2xyz_test,return
end

if nargin==2
    R=radearth;
end

phi=deg2rad(lat);
th=deg2rad(lon);

x=R.*cos(phi).*cos(th);
y=R.*cos(phi).*sin(th);
z=R.*sin(phi);

function[]=latlon2xyz_test
%   'latlon2xyz --t' runs a test.
%reporttest(' LATLON2XYZ ',aresame())