function hndl = plotm(varargin)

%PLOTM  Project 2D line objects onto the current map axes
%
%  PLOTM(lat,lon) projects line objects onto the current
%  map axes.  The input latitude and longitude data must be in
%  the same units as specified in the current map axes.
%  PLOTM will clear the current map if the hold state is off.
%
%  PLOTM(lat,lon,'LineSpec') uses any valid LineSpec string to
%  display the line object.
%
%  PLOTM(lat,lon,'PropertyName',PropertyValue,...) uses
%  the line object properties specified to display the line
%  objects.  Except for xdata, ydata and zdata, all line properties,
%  and styles available through PLOT are supported by PLOTM.
%
%  PLOTM(mat,...) uses a single input matrix, mat = [lat lon],
%  where the first half of the matrix columns represents the
%  latitude data and the second half of the columns represent
%  longitude data.
%
%  h = PLOTM(...) returns the handles to the line objects displayed.
%
%  PLOTM, without any inputs, will activate a GUI to project line
%  objects onto the current map axes.
%
%  See also PLOT3M, PLOT, LINEM, LINE

%  Copyright 1996-1998 by Systems Planning and Analysis, Inc. and The MathWorks, Inc.
%  Written by:  E. Byrns, E. Brown
%   $Revision: 1.7 $    $Date: 1998/08/10 17:51:04 $


if nargin == 0
	linem;  return

else
	lat = varargin{1};

    if nargin >= 2;     lon = varargin{2};
	    else            lon = [];
    end

    if isstr(lon) | nargin == 1
        if size(lat,2) < 2
	        error('Input matrix must have at least two columns')
	    elseif rem(size(lat,2),2)
	        error('Input matrix must have an even number of columns')
	    else
		    indx = (1 + size(lat,2)/2) : size(lat,2);
		    lon = lat(:,indx);    lat(:,indx) = [];
	    end
        varargin(1) = [];
    else
        varargin(1:2) = [];
	end
end

%  Display the map

nextmap;
if ~isempty(varargin)
    [hndl0,msg] = linem(lat,lon,varargin{:});
else
    [hndl0,msg] = linem(lat,lon);
end

if ~isempty(msg);  error(msg);  end

%  Set handle return argument if necessary

if nargout == 1;   hndl = hndl0;   end