# csdms-contrib/slepian_alpha

Switch branches/tags
Nothing to show
Fetching contributors…
Cannot retrieve contributors at this time
24 lines (19 sloc) 874 Bytes
 function [latmax,lonmax]=apex(lat1,lon1,lat2,lon2) % Calculates highest points on a great circle % Input is in radians % % Last modified by fjsimons-at-alum.mit.edu, 06/13/2007 % d = acos(sin(lat1).*sin(lat2)+cos(lat1).*cos(lat2).*cos(lon1-lon2)); % Calculates the great circle distance between two points, in radians d=grcdist([lon1 lat1]*180/pi,[lon2 lat2]*180/pi)/6371; % Calculates the true course at the point d on the line tc1 = acos((sin(lat2)-sin(lat1).*cos(d))./(sin(d).*cos(lat1))); % Highest latitude reached latmax=acos(abs(sin(tc1).*cos(lat1))); % Calculate longitude given latitude on great circle (input in degrees) l12=lon1-lon2; A =sin(lat1).*cos(lat2).*cos(latmax).*sin(l12); B=sin(lat1).*cos(lat2).*cos(latmax).*cos(l12)-cos(lat1).*sin(lat2).*cos(latmax); lonex=atan2(B,A); lonmax=lon1+lonex+(sin(l12)<0)*pi; lonmax=rem(lonmax,2*pi)+(lonmax<0)*2*pi;