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## Copyright (C) 2003 Shai Ayal
##
## This program is free software; you can redistribute it and/or modify it
## under the terms of the GNU General Public License as published by
## the Free Software Foundation; either version 2, or (at your option)
## any later version.
##
## OctPlot is distributed in the hope that it will be useful, but
## WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
## General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with OctPlot; see the file COPYING. If not, write to the Free
## Software Foundation, 59 Temple Place - Suite 330, Boston, MA
## 02111-1307, USA.
## -*- texinfo -*-
## @deftypefn {Function File} {} [@var{C},@var{lev}] = contourc (@var{x},@var{y},@var{z},@var{vv})
## This function computes isolines (countour lines) of the matrix @var{z}.
## parameters @var{x}, @var{y} and @var{vn} are optional.
##
## the return value @var{lev} is a vector of the contour levels.
## The return value @var{c} is a 2xn matrix containing the contour lines
## in the following format
##
## @example
## @var{c} = [lev1 , x1 , x2 , ... , levn , x1 , x2 , ...
## len1 , y1 , y2 , ... , lenn , y1 , y2 , ... ]
## @end example
##
## @noindent
## where contour line n has a level (height) of levn and length of
## lenn.
##
## if @var{x} and @var{y} are ommited they are taken as the row/column
## index of @var{z}. @var{vn} is either a scalar denoting the number of lines
## to compute or a vector contianing the values of the lines. If only one
## value is wanted, set @var{vn}=[val,val];
## If @var{vn} is omitted it defaults to 10
##
## @example
## @var{c}=contourc (@var{x}, @var{y}, @var{z}, linspace(0,2*pi,10))
## @end example
## @end deftypefn
## @seealso{contour}
## Author: shaia
function [c,lev] = contourc(varargin)
if (nargin==1)
vn = 10;
z = varargin{1};
x = 1:size(z,2);
y = 1:size(z,1);
elseif (nargin==2)
vn = varargin{2};
z = varargin{1};
x = 1:size(z,2);
y = 1:size(z,1);
elseif (nargin==3)
vn = 10;
x = varargin{1};
y = varargin{2};
z = varargin{3};
elseif (nargin==4)
vn = varargin{4};
x = varargin{1};
y = varargin{2};
z = varargin{3};
else
error("Wrong number of arguments");
endif
if (isscalar(vn))
vv=linspace(min(min(z)),max(max(z)),vn+2)(2:end-1);
else
vv = unique(sort(vn));
endif
## vectorize the x,y vectors, assuming they are output from meshgrid
if ~isvector(x),
x = x(1,:);
endif
if ~isvector(y),
y = y(:,1);
endif
## make everyone the right dimensions
if(size(x,2)==1)
x = x';
endif
if(size(y,2)==1)
y = y';
endif
## now call __contourc__ for the real work ...
c=__contourc__(x,y,z,vv);
if nargout==2,
lev = vv;
endif
endfunction
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