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scripts/general/nextpow2.m

changeset 10289: 4b124317dc38
parent:c1fff751b5a8
author: John W. Eaton <jwe@octave.org>
date: Tue Feb 09 20:58:55 2010 -0500 (65 minutes ago)
permissions: -rw-r--r--
description: base_properties::set_children: account for hidden children 
     1## Copyright (C) 1995, 1996, 1997, 1999, 2000, 2002, 2004, 2005, 2006,

     2##               2007, 2009 Kurt Hornik

     3##

     4## This file is part of Octave.

     5##

     6## Octave is free software; you can redistribute it and/or modify it

     7## under the terms of the GNU General Public License as published by

     8## the Free Software Foundation; either version 3 of the License, or (at

     9## your option) any later version.

    10##

    11## Octave is distributed in the hope that it will be useful, but

    12## WITHOUT ANY WARRANTY; without even the implied warranty of

    13## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

    14## General Public License for more details.

    15##

    16## You should have received a copy of the GNU General Public License

    17## along with Octave; see the file COPYING.  If not, see

    18## <http://www.gnu.org/licenses/>.

    19

    20## -*- texinfo -*-

    21## @deftypefn {Function File} {} nextpow2 (@var{x})

    22## If @var{x} is a scalar, return the first integer @var{n} such that

    23## @tex

    24## $2^n \ge |x|$.

    25## @end tex

    26## @ifnottex

    27## 2^n >= abs (x).

    28## @end ifnottex

    29##

    30## If @var{x} is a vector, return @code{nextpow2 (length (@var{x}))}.

    31## @seealso{pow2, log2}

    32## @end deftypefn

    33

    34## Author: KH <Kurt.Hornik@wu-wien.ac.at>

    35## Created: 7 October 1994

    36## Adapted-By: jwe

    37

    38function n = nextpow2 (x)

    39

    40  if (nargin != 1)

    41    print_usage ();

    42  endif

    43

    44  if (! (isscalar (x) || isvector (x)))

    45    error ("nextpow2: x must be a scalar or a vector");

    46  endif

    47

    48  t = length (x);

    49  if (t > 1)

    50    x = t;

    51  endif

    52

    53  [f, n] = log2 (abs (x));

    54  if (f == 0.5)

    55    n = n - 1;

    56  endif

    57

    58endfunction