Mercurial > hg > octave-nkf

annotate scripts/general/nextpow2.m @ 5555:dbdba35033a6

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
[project @ 2005-11-30 16:12:04 by jwe]
author jwe
date Wed, 30 Nov 2005 16:12:04 +0000
parents 2a16423e4aa0
children 2618a0750ae6
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
2539
1dca28c213f0 [project @ 1996-11-19 23:54:48 by jwe]
jwe
parents:
diff changeset
1 ## Copyright (C) 1995, 1996 Kurt Hornik
3426
f8dde1807dee [project @ 2000-01-13 08:40:00 by jwe]
jwe
parents: 3407
diff changeset
2 ##
3922
38c61cbf086c [project @ 2002-05-01 06:48:35 by jwe]
jwe
parents: 3426
diff changeset
3 ## This file is part of Octave.
38c61cbf086c [project @ 2002-05-01 06:48:35 by jwe]
jwe
parents: 3426
diff changeset
4 ##
38c61cbf086c [project @ 2002-05-01 06:48:35 by jwe]
jwe
parents: 3426
diff changeset
5 ## Octave is free software; you can redistribute it and/or modify it
38c61cbf086c [project @ 2002-05-01 06:48:35 by jwe]
jwe
parents: 3426
diff changeset
6 ## under the terms of the GNU General Public License as published by
2539
1dca28c213f0 [project @ 1996-11-19 23:54:48 by jwe]
jwe
parents:
diff changeset
7 ## the Free Software Foundation; either version 2, or (at your option)
1dca28c213f0 [project @ 1996-11-19 23:54:48 by jwe]
jwe
parents:
diff changeset
8 ## any later version.
3426
f8dde1807dee [project @ 2000-01-13 08:40:00 by jwe]
jwe
parents: 3407
diff changeset
9 ##
3922
38c61cbf086c [project @ 2002-05-01 06:48:35 by jwe]
jwe
parents: 3426
diff changeset
10 ## Octave is distributed in the hope that it will be useful, but
2539
1dca28c213f0 [project @ 1996-11-19 23:54:48 by jwe]
jwe
parents:
diff changeset
11 ## WITHOUT ANY WARRANTY; without even the implied warranty of
1dca28c213f0 [project @ 1996-11-19 23:54:48 by jwe]
jwe
parents:
diff changeset
12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
3426
f8dde1807dee [project @ 2000-01-13 08:40:00 by jwe]
jwe
parents: 3407
diff changeset
13 ## General Public License for more details.
f8dde1807dee [project @ 2000-01-13 08:40:00 by jwe]
jwe
parents: 3407
diff changeset
14 ##
2539
1dca28c213f0 [project @ 1996-11-19 23:54:48 by jwe]
jwe
parents:
diff changeset
15 ## You should have received a copy of the GNU General Public License
3922
38c61cbf086c [project @ 2002-05-01 06:48:35 by jwe]
jwe
parents: 3426
diff changeset
16 ## along with Octave; see the file COPYING. If not, write to the Free
5307
4c8a2e4e0717 [project @ 2005-04-26 19:24:27 by jwe]
jwe
parents: 5053
diff changeset
17 ## Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
4c8a2e4e0717 [project @ 2005-04-26 19:24:27 by jwe]
jwe
parents: 5053
diff changeset
18 ## 02110-1301, USA.
2539
1dca28c213f0 [project @ 1996-11-19 23:54:48 by jwe]
jwe
parents:
diff changeset
19
3321
6923abb04e16 [project @ 1999-10-26 18:15:30 by jwe]
jwe
parents: 2816
diff changeset
20 ## -*- texinfo -*-
6923abb04e16 [project @ 1999-10-26 18:15:30 by jwe]
jwe
parents: 2816
diff changeset
21 ## @deftypefn {Function File} {} nextpow2 (@var{x})
6923abb04e16 [project @ 1999-10-26 18:15:30 by jwe]
jwe
parents: 2816
diff changeset
22 ## If @var{x} is a scalar, returns the first integer @var{n} such that
6923abb04e16 [project @ 1999-10-26 18:15:30 by jwe]
jwe
parents: 2816
diff changeset
23 ## @iftex
6923abb04e16 [project @ 1999-10-26 18:15:30 by jwe]
jwe
parents: 2816
diff changeset
24 ## @tex
6923abb04e16 [project @ 1999-10-26 18:15:30 by jwe]
jwe
parents: 2816
diff changeset
25 ## $2^n \ge |x|$.
6923abb04e16 [project @ 1999-10-26 18:15:30 by jwe]
jwe
parents: 2816
diff changeset
26 ## @end tex
6923abb04e16 [project @ 1999-10-26 18:15:30 by jwe]
jwe
parents: 2816
diff changeset
27 ## @end iftex
6923abb04e16 [project @ 1999-10-26 18:15:30 by jwe]
jwe
parents: 2816
diff changeset
28 ## @ifinfo
6923abb04e16 [project @ 1999-10-26 18:15:30 by jwe]
jwe
parents: 2816
diff changeset
29 ## 2^n >= abs (x).
6923abb04e16 [project @ 1999-10-26 18:15:30 by jwe]
jwe
parents: 2816
diff changeset
30 ## @end ifinfo
3426
f8dde1807dee [project @ 2000-01-13 08:40:00 by jwe]
jwe
parents: 3407
diff changeset
31 ##
3321
6923abb04e16 [project @ 1999-10-26 18:15:30 by jwe]
jwe
parents: 2816
diff changeset
32 ## If @var{x} is a vector, return @code{nextpow2 (length (@var{x}))}.
6923abb04e16 [project @ 1999-10-26 18:15:30 by jwe]
jwe
parents: 2816
diff changeset
33 ## @end deftypefn
5053
c08cb1098afc [project @ 2004-10-19 23:10:54 by jwe]
jwe
parents: 4030
diff changeset
34 ##
3407
5e0a0b1cba43 [project @ 2000-01-06 03:13:55 by jwe]
jwe
parents: 3321
diff changeset
35 ## @seealso{pow2}
2539
1dca28c213f0 [project @ 1996-11-19 23:54:48 by jwe]
jwe
parents:
diff changeset
36
5428
2a16423e4aa0 [project @ 2005-08-23 18:38:27 by jwe]
jwe
parents: 5307
diff changeset
37 ## Author: KH <Kurt.Hornik@wu-wien.ac.at>
2539
1dca28c213f0 [project @ 1996-11-19 23:54:48 by jwe]
jwe
parents:
diff changeset
38 ## Created: 7 October 1994
1dca28c213f0 [project @ 1996-11-19 23:54:48 by jwe]
jwe
parents:
diff changeset
39 ## Adapted-By: jwe
1dca28c213f0 [project @ 1996-11-19 23:54:48 by jwe]
jwe
parents:
diff changeset
40
1dca28c213f0 [project @ 1996-11-19 23:54:48 by jwe]
jwe
parents:
diff changeset
41 function n = nextpow2 (x)
3426
f8dde1807dee [project @ 2000-01-13 08:40:00 by jwe]
jwe
parents: 3407
diff changeset
42
2539
1dca28c213f0 [project @ 1996-11-19 23:54:48 by jwe]
jwe
parents:
diff changeset
43 if (nargin != 1)
1dca28c213f0 [project @ 1996-11-19 23:54:48 by jwe]
jwe
parents:
diff changeset
44 usage ("nextpow2 (x)");
1dca28c213f0 [project @ 1996-11-19 23:54:48 by jwe]
jwe
parents:
diff changeset
45 endif
1dca28c213f0 [project @ 1996-11-19 23:54:48 by jwe]
jwe
parents:
diff changeset
46
4030
22bd65326ec1 [project @ 2002-08-09 18:58:13 by jwe]
jwe
parents: 3922
diff changeset
47 if (! (isscalar (x) || isvector (x)))
2539
1dca28c213f0 [project @ 1996-11-19 23:54:48 by jwe]
jwe
parents:
diff changeset
48 error ("nextpow2: x must be a scalar or a vector");
1dca28c213f0 [project @ 1996-11-19 23:54:48 by jwe]
jwe
parents:
diff changeset
49 endif
2816
ad4bf2a82b4f [project @ 1997-03-15 21:08:25 by jwe]
jwe
parents: 2539
diff changeset
50
ad4bf2a82b4f [project @ 1997-03-15 21:08:25 by jwe]
jwe
parents: 2539
diff changeset
51 t = length (x);
ad4bf2a82b4f [project @ 1997-03-15 21:08:25 by jwe]
jwe
parents: 2539
diff changeset
52 if (t > 1)
ad4bf2a82b4f [project @ 1997-03-15 21:08:25 by jwe]
jwe
parents: 2539
diff changeset
53 x = t;
ad4bf2a82b4f [project @ 1997-03-15 21:08:25 by jwe]
jwe
parents: 2539
diff changeset
54 endif
3426
f8dde1807dee [project @ 2000-01-13 08:40:00 by jwe]
jwe
parents: 3407
diff changeset
55
2539
1dca28c213f0 [project @ 1996-11-19 23:54:48 by jwe]
jwe
parents:
diff changeset
56 [f, n] = log2 (abs (x));
1dca28c213f0 [project @ 1996-11-19 23:54:48 by jwe]
jwe
parents:
diff changeset
57 if (f == 0.5)
1dca28c213f0 [project @ 1996-11-19 23:54:48 by jwe]
jwe
parents:
diff changeset
58 n = n - 1;
1dca28c213f0 [project @ 1996-11-19 23:54:48 by jwe]
jwe
parents:
diff changeset
59 endif
3426
f8dde1807dee [project @ 2000-01-13 08:40:00 by jwe]
jwe
parents: 3407
diff changeset
60
2539
1dca28c213f0 [project @ 1996-11-19 23:54:48 by jwe]
jwe
parents:
diff changeset
61 endfunction