Mercurial > hg > octave-nkf
comparison scripts/general/diff.m @ 2539:1dca28c213f0
[project @ 1996-11-19 23:54:48 by jwe]
| author | jwe |
|---|---|
| date | Tue, 19 Nov 1996 23:55:06 +0000 |
| parents | |
| children | f37ca3017116 |
comparison
equal
deleted
inserted
replaced
| 2538:6f71af650490 | 2539:1dca28c213f0 |
|---|---|
| 1 ## Copyright (C) 1995, 1996 Kurt Hornik | |
| 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, or (at your option) | |
| 6 ## any later version. | |
| 7 ## | |
| 8 ## This program is distributed in the hope that it will be useful, but | |
| 9 ## WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 10 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| 11 ## General Public License for more details. | |
| 12 ## | |
| 13 ## You should have received a copy of the GNU General Public License | |
| 14 ## along with this file. If not, write to the Free Software Foundation, | |
| 15 ## 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
| 16 | |
| 17 ## usage: diff (x [, k]) | |
| 18 ## | |
| 19 ## If x is a vector of length n, diff (x) is the vector of first | |
| 20 ## differences x(2) - x(1), ..., x(n) - x(n-1). | |
| 21 ## | |
| 22 ## If x is a matrix, diff (x) is the matrix of column differences. | |
| 23 ## diff (x, k), where k is a nonnegative integer, returns the k-th | |
| 24 ## differences. | |
| 25 | |
| 26 ## Author: KH <Kurt.Hornik@ci.tuwien.ac.at> | |
| 27 ## Created: 2 February 1995 | |
| 28 ## Adapted-By: jwe | |
| 29 | |
| 30 function x = diff (x, k) | |
| 31 | |
| 32 if (nargin == 1) | |
| 33 k = 1; | |
| 34 elseif (nargin == 2) | |
| 35 if (! (is_scalar (k) && k == round (k) && k >= 0)) | |
| 36 error ("diff: k must be a nonnegative integer"); | |
| 37 elseif (k == 0) | |
| 38 return; | |
| 39 endif | |
| 40 else | |
| 41 usage ("diff (x [, k]"); | |
| 42 endif | |
| 43 | |
| 44 if (isstr (x)) | |
| 45 error ("diff: symbolic differentiation not (yet) supported"); | |
| 46 elseif (is_vector (x)) | |
| 47 n = length (x); | |
| 48 if (n <= k) | |
| 49 x = []; | |
| 50 else | |
| 51 for i = 1 : k | |
| 52 x = x (2 : (n - i + 1)) - x (1 : (n - i)); | |
| 53 endfor | |
| 54 endif | |
| 55 elseif (is_matrix (x)) | |
| 56 n = rows (x); | |
| 57 if (n <= k) | |
| 58 x = []; | |
| 59 else | |
| 60 for i = 1 : k | |
| 61 x = x (2 : (n - i + 1), :) - x (1: (n - i), :); | |
| 62 endfor | |
| 63 endif | |
| 64 else | |
| 65 x = []; | |
| 66 endif | |
| 67 | |
| 68 endfunction |