Add a useful package (from Source forge) for octave

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

diff --git a/octave_packages/geometry-1.5.0/geom2d/isParallel.m b/octave_packages/geometry-1.5.0/geom2d/isParallel.m
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+++ b/octave_packages/geometry-1.5.0/geom2d/isParallel.m
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+%% Copyright (c) 2011, INRA
+%% 2006-2011, 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{b} = } isParallel (@var{v1}, @var{v2})
+%% @deftypefnx {Function File} {@var{b} = } isParallel (@var{v1}, @var{v2},@var{tol})
+%% Check parallelism of two vectors
+%%
+%%   @var{v1} and @var{v2} are 2 row vectors of length Nd, Nd being the dimension, 
+%%   returns @code{true} if the vectors are parallel, and @code{false} otherwise.
+%%
+%%   Also works when @var{v1} and @var{v2} are two [NxNd] arrays with same number of
+%%   rows. In this case, return a [Nx1] array containing @code{true} at the positions
+%%   of parallel vectors.
+%%
+%%   @var{tol} specifies the accuracy of numerical computation. Default value is 1e-14.
+%%
+%%   Example
+%%
+%% @example
+%%   isParallel([1 2], [2 4])
+%%   ans = 
+%%     1
+%%   isParallel([1 2], [1 3])
+%%   ans = 
+%%     0
+%% @end example
+%%
+%%   @seealso{vectors2d, isPerpendicular, lines2d}
+%% @end deftypefn
+
+%% FIXME or erase me
+%%   Also works when one of @var{v1} or @var{v2} is scalar and the other one is [NxNd]
+%%   array, in this case return [Nx1] results.
+
+function b = isParallel(v1, v2, varargin)
+
+  % default accuracy
+  acc = 1e-14;
+  if ~isempty(varargin)
+      acc = abs(varargin{1});
+  end
+
+  % adapt size of inputs if needed
+  n1 = size(v1, 1);
+  n2 = size(v2, 1);
+  if n1 ~= n2
+      if n1 == 1
+          v1 = v1(ones(n2,1), :);
+      elseif n2 == 1
+          v2 = v2(ones(n1,1), :);
+      end
+  end
+
+  % performs computation
+  if size(v1, 2) == 2
+      b = abs(v1(:, 1) .* v2(:, 2) - v1(:, 2) .* v2(:, 1)) < acc;
+  else
+      % computation in space
+      b = vectorNorm(cross(v1, v2, 2)) < acc;
+  end
+
+endfunction
+
+%!assert (isParallel ([1 2], [2 4]))
+%!assert (!isParallel ([1 2], [1 3]))
+%!error (isParallel (3, rand(4,2)))