function [flat,flon]=convertll(lat,lon)
% convert string positions into numeric decimal degrees
% input latitude and longitude, each in a character string
% output lat and lon in  +/- floating point degrees


%%% START USGS BOILERPLATE -------------% There is no published documentation for these programs- use the 
%  internal comments and help function.
% Programs written in Matlab- as early as 7.2.0.232 (R2006a) and 
% most recent modifications in  v7.8.0 (R2009a)
% Programs ran on PC with Windows XP Professional OS, and RHEL4 linux.
%
% "Although this program has been used by the USGS, no warranty, 
% expressed or implied, is made by the USGS or the United States 
% Government as to the accuracy and functioning of the program 
% and related program material nor shall the fact of distribution 
% constitute any such warranty, and no responsibility is assumed 
% by the USGS in connection therewith."
%%% END USGS BOILERPLATE -------------- 

% programmer:			Susan A. Tarbell
% date:					June 4, 1999
% computer:				PC 
% operating system:	Windows NT
% Matlab 				Version 5.3.0.10183 (R11) on PCWIN

if isempty(lat) == 1
	disp('Status: There is no global latitude value. Default value used.')
	flat=99.9;
else
	latsign=+1;

	llat=length(lat);

	if lat(llat) == 'n' | lat(llat) == 'N'
		latsign = 1;
		lat=lat(1:llat-1);			% remove N sign
		llat=length(lat);				% re-establish length of latitude
	elseif lat(llat) == 's' | lat(llat) == 'S'
		latsign = -1;
		lat=lat(1:llat-1);			% remove S sign
		llat=length(lat);				% re-establish length of latitude
	elseif lat(1) == '-'
		latsign = -1;
		lat =lat(2:llat);				% remove negative sign
		llat=length(lat);				% re-establish length of latitude
	else
		disp('latitude fell through the loop, therefore it must already be degrees!');
	end

	if lat(llat) == ' '
		lat=lat(1:llat-1);			% remove an ending space (if any)
		llat=length(lat);				% re-establish length of latitude
	end									% remove an ending space

	latm=0;								% initialize value
	lats=0;								% initialize value
	flat=[];

	spac=find(lat == ' ');			% find spaces
	if isempty(spac) == 1			% no spaces, assume either whole degrees or decimal degrees
		flat=str2num(lat);
	elseif length(spac) == 1		% get degrees, assume the rest is in decimal minutes
		latd=str2num(lat(1:spac(1)-1));
		latm=str2num(lat((spac(1)+1):llat));
	elseif length(spac) == 2		% assume minutes and seconds
		latd=str2num(lat(1:spac(1)-1));
		latm=str2num(lat((spac(1)+1):(spac(2)-1)));
		lats=str2num(lat((spac(2)+1):llat));
	end
		
	if isempty(flat) == 1			% flat is empty so get the individual components
		lats=lats/60;
		flatm=(latm+lats)/60;
		flat=latd+flatm;
	end
	
	flat=flat*latsign;
end


% now do longitude

if isempty(lat) == 1
	disp('Status: There is no global longitude value. Default value used.')
	flon=999.9;
else
	lonsign=+1;

	llon=length(lon);

	if lon(llon) == 'e' | lon(llon) == 'E'
		lonsign = 1;
		lon=lon(1:llon-1);			% remove e sign
		llon=length(lon);				% re-establish length of lonitude
	elseif lon(llon) == 'w' | lon(llon) == 'W'
		lonsign = -1;
		lon=lon(1:llon-1);			% remove w sign
		llon=length(lon);				% re-establish length of lonitude
	elseif lon(1) == '-'
		lonsign = -1;
		lon =lon(2:llon);				% remove negative sign
		llon=length(lon);				% re-establish length of lonitude	
	else
		disp('longitude fell through the loop! therefore it must already be degrees');
	end
	
	if lon(llon) == ' '
		lon=lon(1:llon-1);			% remove an ending space (if any)
		llon=length(lon);				% re-establish length of lonitude
	end	% remove an ending space
	
	lonm=0;								% initialize value
	lons=0;								% initialize value
	flon=[];
	
	spac=find(lon == ' ');	  		% find spaces
	if isempty(spac) == 1			% no spaces, assume either whole degrees or decimal degrees
		flon=str2num(lon);
	elseif length(spac) == 1		% get degrees, assume the rest is in decimal minutes
		lond=str2num(lon(1:spac(1)-1));
		lonm=str2num(lon((spac(1)+1):llon));
	elseif length(spac) == 2		% assume minutes and seconds
		lond=str2num(lon(1:spac(1)-1));
		lonm=str2num(lon((spac(1)+1):(spac(2)-1)));
		lons=str2num(lon((spac(2)+1):llon));
	end
		
	if isempty(flon) == 1			% flon is empty so get the individual components
		lons=lons/60;
		flonm=(lonm+lons)/60;
		flon=lond+flonm;
	end
	
	flon=flon*lonsign;
	
end
% - - - - - - - - - - - - - - - -  end function  - - - - - - - - - - - - - - - - - - - -