Add a useful package (from Source forge) for octave

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

diff --git a/octave_packages/geometry-1.5.0/geom2d/createHomothecy.m b/octave_packages/geometry-1.5.0/geom2d/createHomothecy.m
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+++ b/octave_packages/geometry-1.5.0/geom2d/createHomothecy.m
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+%% Copyright (c) 2011, INRA
+%% 2009-2011, 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{T} = } createHomothecy (@var{point}, @var{ratio})
+%% Create the the 3x3 matrix of an homothetic transform.
+%
+%   @var{point} is the center of the homothecy, @var{ratio} is its factor.
+%
+%   @seealso{transforms2d, transformPoint, createTranslation}
+%% @end deftypefn
+
+function trans = createHomothecy(point, ratio)
+
+  % extract coordinate of center
+  x0 = point(:,1);
+  y0 = point(:,2);
+
+  % compute coefficients of the matrix
+  m00 = ratio;
+  m01 = 0;
+  m02 = x0*(1-ratio);
+  m10 = 0;
+  m11 = ratio;
+  m12 = y0*(1-ratio);
+
+  % create transformation
+  trans = [m00 m01 m02; m10 m11 m12; 0 0 1];
+
+endfunction
+