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comparison scripts/general/diff.m @ 3426:f8dde1807dee

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[project @ 2000-01-13 08:40:00 by jwe]
author jwe
date Thu, 13 Jan 2000 08:40:53 +0000
parents f37ca3017116
children 434790acb067
comparison
equal deleted inserted replaced
3425:8625164a0a39 3426:f8dde1807dee
1 ## Copyright (C) 1995, 1996 Kurt Hornik 1 ## Copyright (C) 1995, 1996 Kurt Hornik
2 ## 2 ##
3 ## This program is free software; you can redistribute it and/or modify 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 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) 5 ## the Free Software Foundation; either version 2, or (at your option)
6 ## any later version. 6 ## any later version.
7 ## 7 ##
8 ## This program is distributed in the hope that it will be useful, but 8 ## This program is distributed in the hope that it will be useful, but
9 ## WITHOUT ANY WARRANTY; without even the implied warranty of 9 ## WITHOUT ANY WARRANTY; without even the implied warranty of
10 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 10 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 ## General Public License for more details. 11 ## General Public License for more details.
12 ## 12 ##
13 ## You should have received a copy of the GNU General Public License 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, 14 ## along with this file. If not, write to the Free Software Foundation,
15 ## 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. 15 ## 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
16 16
17 ## -*- texinfo -*- 17 ## -*- texinfo -*-
24 ## @end tex 24 ## @end tex
25 ## @end iftex 25 ## @end iftex
26 ## @ifinfo 26 ## @ifinfo
27 ## @var{x}(2) - @var{x}(1), @dots{}, @var{x}(n) - @var{x}(n-1). 27 ## @var{x}(2) - @var{x}(1), @dots{}, @var{x}(n) - @var{x}(n-1).
28 ## @end ifinfo 28 ## @end ifinfo
29 ## 29 ##
30 ## If @var{x} is a matrix, @code{diff (@var{x})} is the matrix of column 30 ## If @var{x} is a matrix, @code{diff (@var{x})} is the matrix of column
31 ## differences. 31 ## differences.
32 ## 32 ##
33 ## The second argument is optional. If supplied, @code{diff (@var{x}, 33 ## The second argument is optional. If supplied, @code{diff (@var{x},
34 ## @var{k})}, where @var{k} is a nonnegative integer, returns the 34 ## @var{k})}, where @var{k} is a nonnegative integer, returns the
35 ## @var{k}-th differences. 35 ## @var{k}-th differences.
36 ## @end deftypefn 36 ## @end deftypefn
37 37
38 ## Author: KH <Kurt.Hornik@ci.tuwien.ac.at> 38 ## Author: KH <Kurt.Hornik@ci.tuwien.ac.at>
39 ## Created: 2 February 1995 39 ## Created: 2 February 1995
40 ## Adapted-By: jwe 40 ## Adapted-By: jwe
41 41
42 function x = diff (x, k) 42 function x = diff (x, k)
43 43
44 if (nargin == 1) 44 if (nargin == 1)
45 k = 1; 45 k = 1;
46 elseif (nargin == 2) 46 elseif (nargin == 2)
47 if (! (is_scalar (k) && k == round (k) && k >= 0)) 47 if (! (is_scalar (k) && k == round (k) && k >= 0))
48 error ("diff: k must be a nonnegative integer"); 48 error ("diff: k must be a nonnegative integer");
50 return; 50 return;
51 endif 51 endif
52 else 52 else
53 usage ("diff (x [, k]"); 53 usage ("diff (x [, k]");
54 endif 54 endif
55 55
56 if (isstr (x)) 56 if (isstr (x))
57 error ("diff: symbolic differentiation not (yet) supported"); 57 error ("diff: symbolic differentiation not (yet) supported");
58 elseif (is_vector (x)) 58 elseif (is_vector (x))
59 n = length (x); 59 n = length (x);
60 if (n <= k) 60 if (n <= k)
61 x = []; 61 x = [];
62 else 62 else
63 for i = 1 : k 63 for i = 1 : k
64 x = x (2 : (n - i + 1)) - x (1 : (n - i)); 64 x = x (2 : (n - i + 1)) - x (1 : (n - i));
65 endfor 65 endfor
66 endif 66 endif
67 elseif (is_matrix (x)) 67 elseif (is_matrix (x))
68 n = rows (x); 68 n = rows (x);
69 if (n <= k) 69 if (n <= k)
70 x = []; 70 x = [];
71 else 71 else
72 for i = 1 : k 72 for i = 1 : k
73 x = x (2 : (n - i + 1), :) - x (1: (n - i), :); 73 x = x (2 : (n - i + 1), :) - x (1: (n - i), :);
74 endfor 74 endfor
75 endif 75 endif
76 else 76 else
77 x = []; 77 x = [];
78 endif 78 endif