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+%% Copyright (c) 2011, INRA
+%% 2010-2011, 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{mid} = } midPoint (@var{p1}, @var{p2})
+%% @deftypefnx {Function File} {@var{mid} = } midPoint (@var{edge})
+%% @deftypefnx {Function File} {[@var{midx}, @var{midy}] = } midPoint (@var{edge})
+%% Middle point of two points or of an edge
+%%
+%% Computes the middle point of the two points @var{p1} and @var{p2}.
+%%
+%% If an edge is given, computes the middle point of the edge given by @var{edge}.
+%% @var{edge} has the format: [X1 Y1 X2 Y2], and @var{mid} has the format [XMID YMID],
+%% with XMID = (X1+X2)/2, and YMID = (Y1+Y2)/2.
+%%
+%% If two output arguments are given, it returns the result as two separate variables or arrays.
+%%
+%% Works also when @var{edge} is a N-by-4 array, in this case the result is a
+%% N-by-2 array containing the midpoint of each edge.
+%%
+%% Example
+%%
+%% @example
+%% p1 = [10 20];
+%% p2 = [30 40];
+%% midPoint([p1 p2])
+%% ans =
+%% 20 30
+%% @end example
+%%
+%% @seealso{edges2d, points2d}
+%% @end deftypefn
+
+function varargout = midPoint(varargin)
+
+ if nargin == 1
+ % input is an edge
+ edge = varargin{1};
+ mid = [mean(edge(:, [1 3]), 2) mean(edge(:, [2 4]), 2)];
+
+ elseif nargin == 2
+ % input are two points
+ p1 = varargin{1};
+ p2 = varargin{2};
+
+ % assert inputs are equal
+ n1 = size(p1, 1);
+ n2 = size(p2, 1);
+ if n1 != n2 && min(n1, n2)>1
+ error('geom2d:midPoint', ...
+ 'Inputs must have same size, or one must have length 1');
+ end
+
+ % compute middle point
+ mid = bsxfun(@plus, p1, p2) / 2;
+ end
+
+ % process output arguments
+ if nargout<=1
+ varargout{1} = mid;
+ else
+ varargout = {mid(:,1), mid(:,2)};
+ end
+
+endfunction
+
+%!test
+%! p1 = [10 20];
+%! p2 = [30 40];
+%! exp = [20 30];
+%! mid = midPoint(p1, p2);
+%! assert (mid, exp);
+
+%!test
+%! p1 = [ ...
+%! 10 20 ; ...
+%! 30 40 ; ...
+%! 50 60 ; ...
+%! ];
+%! p2 = [ ...
+%! 30 40; ...
+%! 50 60; ...
+%! 70 80];
+%! exp = [...
+%! 20 30; ...
+%! 40 50; ...
+%! 60 70];
+%! mid = midPoint(p1, p2);
+%! assert (mid, exp);
+
+%!test
+%! p1 = [30 40];
+%! p2 = [ ...
+%! 30 40; ...
+%! 50 60; ...
+%! 70 80];
+%! exp = [...
+%! 30 40; ...
+%! 40 50; ...
+%! 50 60];
+%! mid = midPoint(p1, p2);
+%! assert (mid, exp);
+
+%!test
+%! p1 = [ ...
+%! 10 20 ; ...
+%! 30 40 ; ...
+%! 50 60 ; ...
+%! ];
+%! p2 = [30 40];
+%! exp = [...
+%! 20 30; ...
+%! 30 40; ...
+%! 40 50];
+%! mid = midPoint(p1, p2);
+%! assert (mid, exp);
+
+%!test
+%! p1 = [ ...
+%! 10 20 ; ...
+%! 30 40 ; ...
+%! 50 60 ; ...
+%! ];
+%! p2 = [30 40];
+%! expX = [20 ; 30 ; 40];
+%! expY = [30 ; 40 ; 50];
+%! [x y] = midPoint(p1, p2);
+%! assert (x, expX);
+%! assert (y, expY);
+
+%!test
+%! edge = [10 20 30 40];
+%! exp = [20 30];
+%! mid = midPoint(edge);
+%! assert (mid, exp);
+%! edge = [10 20 30 40; 30 40 50 60; 50 60 70 80];
+%! exp = [20 30;40 50; 60 70];
+%! mid = midPoint(edge);
+%! assert (mid, exp);
+