annotate scripts/general/nextpow2.m @ 19697:4197fc428c7d

maint: Update copyright notices for 2015.
author John W. Eaton <jwe@octave.org>
date Wed, 11 Feb 2015 14:19:08 -0500
parents d63878346099
children 511b3ae4872b
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1 ## Copyright (C) 1995-2015 Kurt Hornik
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2 ##
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3 ## This file is part of Octave.
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4 ##
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5 ## Octave is free software; you can redistribute it and/or modify it
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6 ## under the terms of the GNU General Public License as published by
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7 ## the Free Software Foundation; either version 3 of the License, or (at
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8 ## your option) any later version.
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9 ##
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10 ## Octave is distributed in the hope that it will be useful, but
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11 ## WITHOUT ANY WARRANTY; without even the implied warranty of
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12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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13 ## General Public License for more details.
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14 ##
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15 ## You should have received a copy of the GNU General Public License
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16 ## along with Octave; see the file COPYING. If not, see
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17 ## <http://www.gnu.org/licenses/>.
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18
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19 ## -*- texinfo -*-
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20 ## @deftypefn {Function File} {} nextpow2 (@var{x})
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21 ## If @var{x} is a scalar, return the first integer @var{n} such that
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22 ## @tex
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23 ## $2^n \ge |x|$.
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24 ## @end tex
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25 ## @ifnottex
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26 ## 2^n @geq{} abs (x).
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27 ## @end ifnottex
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28 ##
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29 ## If @var{x} is a vector, return @code{nextpow2 (length (@var{x}))}.
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30 ## @seealso{pow2, log2}
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31 ## @end deftypefn
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32
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33 ## Author: KH <Kurt.Hornik@wu-wien.ac.at>
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34 ## Created: 7 October 1994
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35 ## Adapted-By: jwe
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36
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37 function n = nextpow2 (x)
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38
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39 if (nargin != 1)
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40 print_usage ();
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41 endif
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42
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43 if (! (isscalar (x) || isvector (x)))
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44 error ("nextpow2: X must be a scalar or a vector");
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45 endif
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47 t = length (x);
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48 if (t > 1)
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49 x = t;
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50 endif
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51
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52 [f, n] = log2 (abs (x));
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53 if (f == 0.5)
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54 n = n - 1;
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55 endif
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56
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57 endfunction
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60 %!assert (nextpow2 (16), 4)
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61 %!assert (nextpow2 (17), 5)
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62 %!assert (nextpow2 (31), 5)
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63 %!assert (nextpow2 (-16), 4)
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64 %!assert (nextpow2 (-17), 5)
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65 %!assert (nextpow2 (-31), 5)
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66 %!assert (nextpow2 (1:17), 5)
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68 %!error nexpow2 ()
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69 %!error nexpow2 (1, 2)
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