## Copyright (C) 2009 VZLU Prague, a.s., Czech Republic ## ## Author: Jaroslav Hajek ## ## This program is free software; you can redistribute it and/or modify ## it under the terms of the GNU General Public License as published by ## the Free Software Foundation; either version 3 of the License, or ## (at your option) any later version. ## ## This program is distributed in the hope that it will be useful, ## but WITHOUT ANY WARRANTY; without even the implied warranty of ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ## GNU General Public License for more details. ## ## You should have received a copy of the GNU General Public License ## along with this program; see the file COPYING. If not, see ## <http://www.gnu.org/licenses/>. ## -*- texinfo -*- ## @deftypefn{Function File} {[@var{xs}, @var{ys}] =} unresamp2 (@var{x}, @var{y}, @var{n}) ## Perform a uniform resampling of a planar curve. ## The arrays @var{x} and @var{y} specify x and y coordinates of the points of the curve. ## On return, the same curve is approximated by @var{xs}, @var{ys} that have length @var{n} ## and the distances between successive points are approximately equal. ## @end deftypefn function [xs, ys] = unresamp2 (x, y, n) if (! isvector (x) || ! size_equal (x, y) || ! isscalar (n)) print_usage (); endif if (rows (x) == 1) rowvec = true; x = x.'; y = y.'; else rowvec = false; endif # first differences dx = diff (x); dy = diff (y); # arc lengths ds = hypot (dx, dy); # cumulative integral s = cumsum ([0; ds]); # generate sample points i = linspace (0, s(end), n); if (! rowvec) i = i.'; endif # and resample xs = interp1 (s, x, i); ys = interp1 (s, y, i); endfunction %!demo %! R = 2; r = 3; d = 1.5; %! th = linspace (0, 2*pi, 1000); %! x = (R-r) * cos (th) + d*sin ((R-r)/r * th); %! y = (R-r) * sin (th) + d*cos ((R-r)/r * th); %! x += 0.3*exp (-(th-0.8*pi).^2); %! y += 0.4*exp (-(th-0.9*pi).^2); %! %! [xs, ys] = unresamp2 (x, y, 40); %! plot (x, y, "-", xs, ys, "*"); %! title ("uniform resampling")

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