/usr/share/octave/packages/geometry-1.7.0/polygons2d/simplifypolygon.m is in octave-geometry 1.7.0-1build1.
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## Copyright (C) 2004-2011 INRA - CEPIA Nantes - MIAJ (Jouy-en-Josas)
## Copyright (C) 2012 Adapted to Octave by Juan Pablo Carbajal <carbajal@ifi.uzh.ch>
## All rights reserved.
##
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## modification, are permitted provided that the following conditions are met:
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## -*- texinfo -*-
## @deftypefn {Function File} {@var{spoly} = } simplifypolygon (@var{poly})
## Simplify a polygon using the Ramer-Douglas-Peucker algorithm.
##
## @var{poly} is a N-by-2 matrix, each row representing a vertex.
##
## @seealso{simplifypolyline, shape2polygon}
## @end deftypefn
function polygonsimp = simplifypolygon (polygon, varargin)
polygonsimp = simplifypolyline (polygon,varargin{:});
# Remove parrallel consecutive edges
PL = polygonsimp(1:end-1,:);
PC = polygonsimp(2:end,:);
PR = polygonsimp([3:end 1],:);
a = PL - PC;
b = PR - PC;
tf = find (isParallel(a,b))+1;
polygonsimp (tf,:) = [];
endfunction
%!test
%! P = [0 0; 1 0; 0 1];
%! P2 = [0 0; 0.1 0; 0.2 0; 0.25 0; 1 0; 0 1; 0 0.7; 0 0.6; 0 0.3; 0 0.1];
%! assert(simplifypolygon (P2),P,min(P2(:))*eps)
%!demo
%!
%! P = [0 0; 1 0; 0 1];
%! P2 = [0 0; 0.1 0; 0.2 0; 0.25 0; 1 0; 0 1; 0 0.7; 0 0.6; 0 0.3; 0 0.1];
%! Pr = simplifypolygon (P2);
%!
%! cla
%! drawPolygon(P,'or;Reference;');
%! hold on
%! drawPolygon(P2,'x-b;Redundant;');
%! drawPolygon(Pr,'*g;Simplified;');
%! hold off
%!
%! # --------------------------------------------------------------------------
%! # The two polygons describe the same figure, a triangle. Extra points are
%! # removed form the redundant one.
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