function [CS,H]=econtour(arg1,arg2,arg3,arg4,arg5,arg6,arg7,arg8,arg9,arg10,arg11, ...
    arg12,arg13,arg14,arg15,arg16,arg17,arg18,arg19,arg20);
%	The function ECONTOUR draws contours returning a contour structure CS.
%	ECONTOUR is an extended contouring package.
%	ECONTOUR(Z) is a contour plot of matrix Z treating the values in Z
%	as heights above a plane.
%	ECONTOUR(X,Y,Z), where X and Y are vectors, specifies the X and Y
%	axes used on the plot. X and Y can also be matrices of the same
%	size as Z, in which case they specify a surface in an identical
%	manner as SURFACE.
%	ECONTOUR(Z,N) and ECONTOUR(X,Y,Z,N) draw N contour lines, 
%	overriding the default automatic value.
%	ECONTOUR(Z,V) and ECONTOUR(X,Y,Z,V) draw LENGTH(V) contour lines 
%	at the values specified in vector V.
%     
%	Following the numeric arguments can be a number of string
%	arguments:
%	'label' to add annotation, followed by a (optional) numerical
%	argument that sets the label spacing in 'points' (default 144);
%	'fill' to do a block fill e.g., ECONTOUR(...,'label');
%	and any number of property/value pairs where the properties are
%	text properties (beginning with 'Font...' or 'Rotation') or line 
%	properties (beginning with 'line...' or 'color'). Color and
%	linetype can also be specified as in the PLOT command.
%	e.g., ECONTOUR(...,'fontsize',8,'linewidth',3,'--r');
         
%	Rich Pawlowicz (IOS)  rich@ios.bc.ca	12 Dec. 1994 Initial


% Option defaults

do_label=0;
do_fill=0;

% Parse options
numarg_for_call=['arg1'];
linarg_for_call=[];
textarg_for_call=[];

ii=2;
while (ii<=nargin),
 arg=eval(['arg' int2str(ii)]);
 if (isstr(arg)),
   xarg=[arg '       '];
   if (lower(xarg(1:3))=='lab'),
    do_label=1;
    if (ii<nargin),    % Check if label interval set
      if ~isstr(eval(['arg' int2str(ii+1)])),
        ii=ii+1;
        textarg_for_call=[textarg_for_call ',''' arg ''',arg' int2str(ii)];
      end;
    end;
   elseif (lower(xarg(1:3))=='fil'),
    do_fill=1;
   elseif (lower(xarg(1:3))=='lin' | lower(xarg(1:3))=='col'),
     ii=ii+1;
     linarg_for_call=[linarg_for_call ',''' arg ''',arg' int2str(ii) ];
   elseif (lower(xarg(1:3))=='fon' | lower(xarg(1:3))=='rot' ),
     ii=ii+1;
     textarg_for_call=[textarg_for_call ',''' arg ''',arg' int2str(ii)];
   elseif ( length(arg)<=3 ),
     colr=isletter(arg);
     if any(colr),
       linarg_for_call=[linarg_for_call ',''color'',''' arg(colr) '''' ];
     end;
     if any(~colr),
       linarg_for_call=[linarg_for_call ',''linestyle'',''' arg(~colr) '''' ];
     end;
   else
     error(['invalid argument ' eval(['arg' int2str(ii)])]);
   end;
 else  % numerical argument
   numarg_for_call = [numarg_for_call ',arg' int2str(ii) ];
 end;
 ii=ii+1;
end;

% Do the calls

% Preserve hold state at exit
holdon=ishold;

if (do_label | do_fill ),
 if do_fill,
   eval(['[CS,H]=contourfill(' numarg_for_call ');']);
   hold on;
 end;
 if do_label,
   eval(['CS=cntrsurf(' numarg_for_call ');']);
   eval(['H=eclabel(CS' linarg_for_call textarg_for_call ');']);
   hold off;
 end;
else         % The standard option
 eval(['CS=cntrsurf(' numarg_for_call ');']);
 k=1;
 eval(['H=plot(CS(1,k+[1:CS(2,k)]),CS(2,k+[1:CS(2,k)])' linarg_for_call ');']);
 k=k+1+CS(2,k); 
 while (k<size(CS,2)),
  eval(['H=[H;line(CS(1,k+[1:CS(2,k)]),CS(2,k+[1:CS(2,k)])' linarg_for_call ')];']);
  k=k+1+CS(2,k);
 end;
end;


if (holdon), hold on; else hold off; end;