functionfilename=geoid_file(name,dir)%GEOID_FILE Return filename for geoid data%% filename = geoid_file(name, dir). See the documentation on geoid_load.ifnargin<1||isempty(name)name=getenv('GEOGRAPHICLIB_GEOID_NAME');ifisempty(name)name='egm96-5';endendifnargin<2||isempty(dir)dir=getenv('GEOGRAPHICLIB_GEOID_PATH');ifisempty(dir)dir=getenv('GEOGRAPHICLIB_DATA');ifisempty(dir)ifispcdir='C:/ProgramData/GeographicLib';elsedir='/usr/local/share/GeographicLib';endenddir=[dir,'/geoids'];endendfilename=[dir,'/',name,'.pgm'];end