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[project @ 2006-10-10 16:10:25 by jwe]
author jwe
date Tue, 10 Oct 2006 16:10:31 +0000
parents 2618a0750ae6
children 93c65f2a5668
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1 ## Copyright (C) 1995, 1996 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 2, or (at your option)
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8 ## 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, write to the Free
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17 ## Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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18 ## 02110-1301, USA.
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19
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20 ## -*- texinfo -*-
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21 ## @deftypefn {Function File} {} nextpow2 (@var{x})
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22 ## If @var{x} is a scalar, returns the first integer @var{n} such that
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23 ## @iftex
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24 ## @tex
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25 ## $2^n \ge |x|$.
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26 ## @end tex
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27 ## @end iftex
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28 ## @ifinfo
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29 ## 2^n >= abs (x).
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30 ## @end ifinfo
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31 ##
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32 ## If @var{x} is a vector, return @code{nextpow2 (length (@var{x}))}.
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33 ## @seealso{pow2}
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34 ## @end deftypefn
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35
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36 ## Author: KH <Kurt.Hornik@wu-wien.ac.at>
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37 ## Created: 7 October 1994
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38 ## Adapted-By: jwe
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39
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40 function n = nextpow2 (x)
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41
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42 if (nargin != 1)
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43 print_usage ();
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44 endif
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45
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46 if (! (isscalar (x) || isvector (x)))
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47 error ("nextpow2: x must be a scalar or a vector");
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48 endif
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49
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50 t = length (x);
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51 if (t > 1)
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52 x = t;
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53 endif
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54
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55 [f, n] = log2 (abs (x));
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56 if (f == 0.5)
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57 n = n - 1;
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58 endif
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59
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60 endfunction