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1 ## Copyright (C) 1995, 1996 Kurt Hornik |
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2 ## |
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3 ## This program is free software; you can redistribute it and/or modify |
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4 ## it under the terms of the GNU General Public License as published by |
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5 ## the Free Software Foundation; either version 2, or (at your option) |
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6 ## any later version. |
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7 ## |
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8 ## This program is distributed in the hope that it will be useful, but |
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9 ## WITHOUT ANY WARRANTY; without even the implied warranty of |
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10 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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11 ## General Public License for more details. |
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12 ## |
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13 ## You should have received a copy of the GNU General Public License |
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14 ## along with this file. If not, write to the Free Software Foundation, |
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15 ## 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
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16 |
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17 ## -*- texinfo -*- |
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18 ## @deftypefn {Function File} {} nextpow2 (@var{x}) |
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19 ## If @var{x} is a scalar, returns the first integer @var{n} such that |
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20 ## @iftex |
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21 ## @tex |
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22 ## $2^n \ge |x|$. |
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23 ## @end tex |
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24 ## @end iftex |
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25 ## @ifinfo |
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26 ## 2^n >= abs (x). |
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27 ## @end ifinfo |
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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 ## @end deftypefn |
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31 |
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32 ## See also: pow2 |
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33 |
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34 ## Author: KH <Kurt.Hornik@ci.tuwien.ac.at> |
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35 ## Created: 7 October 1994 |
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36 ## Adapted-By: jwe |
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37 |
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38 function n = nextpow2 (x) |
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39 |
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40 if (nargin != 1) |
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41 usage ("nextpow2 (x)"); |
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42 endif |
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43 |
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44 if (! (is_scalar (x) || is_vector (x))) |
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45 error ("nextpow2: x must be a scalar or a vector"); |
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46 endif |
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47 |
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48 t = length (x); |
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49 if (t > 1) |
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50 x = t; |
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51 endif |
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52 |
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53 [f, n] = log2 (abs (x)); |
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54 if (f == 0.5) |
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55 n = n - 1; |
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56 endif |
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57 |
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58 endfunction |
