Mercurial > forge
comparison main/splines/spline.m @ 0:6b33357c7561 octave-forge
Initial revision
| author | pkienzle |
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| date | Wed, 10 Oct 2001 19:54:49 +0000 |
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| -1:000000000000 | 0:6b33357c7561 |
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| 1 ## Copyright (C) 2000 Kai Habel | |
| 2 ## | |
| 3 ## This program is free software; you can redistribute it and/or modify | |
| 4 ## it under the terms of the GNU General Public License as published by | |
| 5 ## the Free Software Foundation; either version 2 of the License, or | |
| 6 ## (at your option) any later version. | |
| 7 ## | |
| 8 ## This program is distributed in the hope that it will be useful, | |
| 9 ## but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 10 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
| 11 ## GNU General Public License for more details. | |
| 12 ## | |
| 13 ## You should have received a copy of the GNU General Public License | |
| 14 ## along with this program; if not, write to the Free Software | |
| 15 ## Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
| 16 | |
| 17 ## -*- texinfo -*- | |
| 18 ## @deftypefn {Function File} {@var{pp} = } spline (@var{x}, @var{y}) | |
| 19 ## @deftypefnx {Function File} {@var{yi} = } spline (@var{x}, @var{y}, @var{xi}) | |
| 20 ## cubic spline interpolation | |
| 21 ## | |
| 22 ## @seealso{ppval, csapi, csape} | |
| 23 ## @end deftypefn | |
| 24 | |
| 25 | |
| 26 ## Author: Kai Habel <kai.habel@gmx.de> | |
| 27 ## Date: 3. dec 2000 | |
| 28 ## 2001-02-08 Paul Kienzle | |
| 29 ## * copied from csapi.m | |
| 30 | |
| 31 function ret = spline (x, y, xi) | |
| 32 | |
| 33 ret = csape (x, y, 'not-a-knot'); | |
| 34 | |
| 35 if (nargin == 3) | |
| 36 ret = ppval (ret, xi); | |
| 37 endif | |
| 38 | |
| 39 endfunction | |
| 40 | |
| 41 %!demo | |
| 42 %! x = 0:10; y = sin(x); | |
| 43 %! xspline = 0:0.1:10; yspline = spline(x,y,xspline); | |
| 44 %! title("spline fit to points from sin(x)"); | |
| 45 %! plot(xspline,sin(xspline),";original;",... | |
| 46 %! xspline,yspline,"-;interpolation;",... | |
| 47 %! x,y,"+;interpolation points;"); | |
| 48 %! %-------------------------------------------------------- | |
| 49 %! % confirm that interpolated function matches the original | |
| 50 | |
| 51 %!shared x,y | |
| 52 %! x = [0:10]'; y = sin(x); | |
| 53 %!assert (spline(x,y,x), y); | |
| 54 %!assert (spline(x,y,x'), y'); | |
| 55 %!assert (spline(x',y',x'), y'); | |
| 56 %!assert (spline(x',y',x), y); | |
| 57 %!assert (isempty(spline(x',y',[]))); | |
| 58 %!assert (isempty(spline(x,y,[]))); | |
| 59 %!assert (spline(x,[y,y],x), [spline(x,y,x),spline(x,y,x)]) |