Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / splines-1.0.7 / fnplt.m

diff --git a/octave_packages/splines-1.0.7/fnplt.m b/octave_packages/splines-1.0.7/fnplt.m
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+## Copyright (C) 2000  Kai Habel
+##
+## 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 2 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; If not, see <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} { } fnplt (@var{pp}, '@var{plt}')
+## plots spline 
+##
+## @seealso{ppval, spline, csape}
+## @end deftypefn
+
+## Author:  Kai Habel <kai.habel@gmx.de>
+## Date: 3. dec 2000
+## 2001-02-19 Paul Kienzle
+##   * use pp.x rather than just x in linspace; add plt parameter
+##   * return points instead of plotting them if desired
+##   * also plot control points
+##   * added demo
+
+function [x, y] = fnplt (pp, plt)
+
+  if (nargin < 1 || nargin > 2)
+    usage ("[x, y] = fnplt (pp [, plotstring])");
+  endif
+  if (nargin < 2)
+    plt = "r;;";
+  endif
+  xi = linspace(min(pp.x),max(pp.x),256)';
+  pts = ppval(pp,xi);
+  if nargout == 2
+    x = xi;
+    y = pts;
+  elseif nargout == 1
+    x = [xi, pts];
+  else
+    plot(xi,pts,plt,pp.x,ppval(pp,pp.x),"bx;;");
+  endif
+
+endfunction
+
+%!demo
+%! x = [ 0; sort(rand(25,1)); 1 ];
+%! pp = csape (x, sin (2*pi*3*x), 'periodic');
+%! axis([0,1,-2,2]); 
+%! title('Periodic spline reconstruction of randomly sampled sine');
+%! fnplt (pp,'r;reconstruction;'); 
+%! t=linspace(0,1,100); y=sin(2*pi*3*t);
+%! hold on; plot(t,y,'g;ideal;'); hold off;
+%! axis; title("");