ellradii.m

Geodetic tools to be used in navigation analysis

function [rm,rp,rl]=ellradii(lat,a,e2)
% ELLRADII  Computers radii of curvature at at a given latitude for
%   a given ellipsoid major semi-axis and eccentricity.
% Version: 30 May 04
% Useage:  [rm,rp,rl]=ellradii(lat,a,e2)
% Input:   lat  - vector of lats of local system origins (rad)
%          a    - ref. ellipsoid major semi-axis
%          e2   - ref. ellipsoid eccentricity squared
% Output:  rm   - radius of curvature of meridian/longitude ellipse
%          rp   - radius of curvature of prime vertical
%          rl   - radius of curvature of latitude circle
rp=a./sqrt(1-e2.*sin(lat).^2);
rm=rp.*(1-e2)./(1-e2.*sin(lat).^2);
rl=rp*cos(lat);