Add a useful package (from Source forge) for octave

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

diff --git a/octave_packages/geometry-1.5.0/geom2d/radicalAxis.m b/octave_packages/geometry-1.5.0/geom2d/radicalAxis.m
new file mode 100644 (file)
index 0000000..c50483b
--- /dev/null
+++ b/octave_packages/geometry-1.5.0/geom2d/radicalAxis.m
@@ -0,0 +1,88 @@
+%% Copyright (c) 2011, INRA
+%% 2004-2011, 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{line} = } radicalAxis (@var{circle1}, @var{circle2})
+%% Compute the radical axis (or radical line) of 2 circles
+%%
+%%   L = radicalAxis(C1, C2)
+%%   Computes the radical axis of 2 circles.
+%%
+%%   Example
+%%   C1 = [10 10 5];
+%%   C2 = [60 50 30];
+%%   L = radicalAxis(C1, C2);
+%%   hold on; axis equal;axis([0 100 0 100]); 
+%%   drawCircle(C1);drawCircle(C2);drawLine(L);
+%%
+%%   Ref:
+%%   http://mathworld.wolfram.com/RadicalLine.html
+%%   http://en.wikipedia.org/wiki/Radical_axis
+%%
+%%   @seealso{lines2d, circles2d, createCircle}
+%%
+%% @end deftypefn
+
+function line = radicalAxis(circle1, circle2)
+
+  % extract circles parameters
+  x1 = circle1(:,1);
+  x2 = circle2(:,1);
+  y1 = circle1(:,2);
+  y2 = circle2(:,2);
+  r1 = circle1(:,3);
+  r2 = circle2(:,3);
+
+  % distance between each couple of centers
+  dist  = sqrt((x2-x1).^2 + (y2-y1).^2);
+
+  % relative position of intersection point of 
+  % the radical line with the line joining circle centers
+  d = (dist.^2 + r1.^2 - r2.^2) * .5 ./ dist;
+
+  % compute angle of radical axis
+  angle = lineAngle(createLine([x1 y1], [x2 y2]));
+  cot = cos(angle);
+  sit = sin(angle);
+
+  % parameters of the line
+  x0 = x1 + d*cot;
+  y0 = y1 + d*sit;
+  dx = -sit;
+  dy = cot;
+
+  % concatenate into one structure
+  line = [x0 y0 dx dy];
+
+endfunction
+