% SURF SURF Surface Plot Function
% 
% Usage
% 
% This routine is used to create a surface plot of data.  A 
% surface plot is a 3D surface defined by the xyz coordinates
% of its vertices and optionally by the color at the vertices.
% The most general syntax for the surf function is
% 
%   h = surf(X,Y,Z,C,properties...)
% 
% Where X is a matrix or vector of x coordinates, Y is a
% matrix or vector of y coordinates, Z is a 2D matrix of
% coordinates, and C is a 2D matrix of color values (the colormap
% for the current fig is applied).  In general, X and Y should
% be the same size as Z, but FreeMat will expand vectors to match
% the matrix if possible.
% If you want the color of the surface to be defined by the height
% of the surface, you can omit C
% 
%   h = surf(X,Y,Z,properties...)
% 
% in which case C=Z.  You can also eliminate the X and Y
% matrices in the specification
% 
%   h = surf(Z,properties)
% 
% in which case they are set to 1:size(Z,2) and 1:size(Y,2)
% respectively.
% You can also specify a handle as the target of the surf command
% via
% 
%   h = surf(handle,...)
% 

% Copyright (c) 2002-2006 Samit Basu

function ohandle = surf(varargin)
   % Check for an axes handle
   if (nargin>=2)
      if (isnumeric(varargin{1}) & (length(varargin{1})==1) & ...
         ishandle(varargin{1},'axes'))
         handle = varargin{1}(1);
         varargin(1) = [];
         nargin = nargin - 1;
      else   
         handle = newplot;
      end
else
   handle = newplot;
end
  saveca = gca;
  axes(handle);
  % search for the propertyname/value pairs
  propstart = 0;
  if (nargin > 2)
    propstart = nargin-1;
    while ((propstart >= 1) & isa(varargin{propstart},'string') & ...
    pvalid('line',varargin{propstart}))
      propstart = propstart - 2;
    end
    propstart = propstart + 2;
  end
  propset = {};
  if ((propstart > 0) & (propstart < nargin))
     propset = varargin(propstart:end);
     varargin(propstart:end) = [];
  end
  if (length(varargin) == 0)
    h = surface(propset{:});
  elseif (length(varargin) == 1)
    h = surface('zdata',varargin{1},propset{:});
  elseif (length(varargin) == 3)
    h = surface('xdata',varargin{1},'ydata',varargin{2},...
	'zdata',varargin{3},propset{:});
  elseif (length(varargin) == 4)
    h = surface('xdata',varargin{1},'ydata',varargin{2},...
	'zdata',varargin{3},'cdata',varargin{4},propset{:});
  else
    error('Unrecognized arguments to surf command');
  end
axes(saveca);
if (nargout > 0)
    ohandle = h;
end