Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / geometry-1.5.0 / geom2d / enclosingCircle.m

diff --git a/octave_packages/geometry-1.5.0/geom2d/enclosingCircle.m b/octave_packages/geometry-1.5.0/geom2d/enclosingCircle.m
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+++ b/octave_packages/geometry-1.5.0/geom2d/enclosingCircle.m
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+%% Copyright (c) 2011, INRA
+%% 2007-2011, David Legland <david.legland@grignon.inra.fr>
+%% 2011 Adapted to Octave by Juan Pablo Carbajal <carbajal@ifi.uzh.ch>
+%%
+%% All rights reserved.
+%% (simplified BSD License)
+%%
+%% Redistribution and use in source and binary forms, with or without
+%% modification, are permitted provided that the following conditions are met:
+%%
+%% 1. Redistributions of source code must retain the above copyright notice, this
+%%    list of conditions and the following disclaimer.
+%%     
+%% 2. Redistributions in binary form must reproduce the above copyright notice, 
+%%    this list of conditions and the following disclaimer in the documentation
+%%    and/or other materials provided with the distribution.
+%%
+%% THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+%% AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+%% IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+%% ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+%% LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
+%% CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+%% SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
+%% INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+%% CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+%% ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+%% POSSIBILITY OF SUCH DAMAGE.
+%%
+%% The views and conclusions contained in the software and documentation are
+%% those of the authors and should not be interpreted as representing official
+%% policies, either expressed or implied, of copyright holder.
+
+%% -*- texinfo -*-
+%% @deftypefn {Function File} {@var{circle} = } enclosingCircle (@var{pts})
+%% Find the minimum circle enclosing a set of points.
+%%
+%%   CIRCLE = enclosingCircle(POINTS);
+%%   compute cirlce CIRCLE=[xc yc r] which enclose all points POINTS given
+%%   as an [Nx2] array.
+%%
+%%
+%%   Rewritten from a file from
+%%           Yazan Ahed 
+%%   which was rewritten from a Java applet by Shripad Thite :
+%%   @url{http://heyoka.cs.uiuc.edu/~thite/mincircle/}
+%%
+%%   @seealso{circles2d, points2d, boxes2d}
+%% @end deftypefn
+
+function circle = enclosingCircle(pts)
+
+  % works on convex hull : it is faster
+  pts = pts(convhull(pts(:,1), pts(:,2)), :);
+
+  circle = recurseCircle(size(pts, 1), pts, 1, zeros(3, 2));
+
+endfunction
+
+function circ = recurseCircle(n, p, m, b)
+%    n: number of points given
+%    m: an argument used by the function. Always use 1 for m.
+%    bnry: an argument (3x2 array) used by the function to set the points that 
+%          determines the circle boundry. You have to be careful when choosing this
+%          array's values. I think the values should be somewhere outside your points
+%          boundary. For my case, for example, I know the (x,y) I have will be something
+%          in between (-5,-5) and (5,5), so I use bnry as:
+%                       [-10 -10
+%                        -10 -10
+%                        -10 -10]
+
+
+  if m==4
+      circ = createCircle(b(1,:), b(2,:), b(3,:));
+      return;
+  end
+
+  circ = [Inf Inf 0];
+
+  if m == 2
+      circ = [b(1,1:2) 0];
+  elseif m == 3
+      c = (b(1,:) + b(2,:))/2;
+      circ = [c distancePoints(b(1,:), c)];
+  end
+
+
+  for i = 1:n
+      if distancePoints(p(i,:), circ(1:2)) > circ(3)
+          if sum(b(:,1)==p(i,1) & b(:,2)==p(i,2)) == 0
+              b(m,:) = p(i,:);
+              circ = recurseCircle(i, p, m+1, b);
+          end
+      end
+  end
+
+endfunction
+