scripts/specfun/pow2.m

## Copyright (C) 1995, 1996, 1999, 2000, 2002, 2004, 2005, 2006, 2007,
##               2008, 2009 Kurt Hornik
##
## This file is part of Octave.
##
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## under the terms of the GNU General Public License as published by
## the Free Software Foundation; either version 3 of the License, or (at
## your option) any later version.
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## General Public License for more details.
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## along with Octave; see the file COPYING.  If not, see
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## -*- texinfo -*-
## @deftypefn {Mapping Function} {} pow2 (@var{x})
## @deftypefnx {Mapping Function} {} pow2 (@var{f}, @var{e})
## With one argument, computes
## @tex
## $2^x$
## @end tex
## @ifnottex
## 2 .^ x
## @end ifnottex
## for each element of @var{x}.
##
## With two arguments, returns
## @tex
## $f \cdot 2^e$.
## @end tex
## @ifnottex
## f .* (2 .^ e).
## @end ifnottex
## @seealso{log2, nextpow2}
## @end deftypefn

## Author: AW <Andreas.Weingessel@ci.tuwien.ac.at>
## Created: 17 October 1994
## Adapted-By: jwe

function y = pow2 (f, e)

  if (nargin == 1)
    y = 2 .^ f;
  elseif (nargin == 2)
    y = f .* (2 .^ e);
  else
    print_usage ();
  endif

endfunction

%!test
%! x = [3, 0, -3];
%! v = [8, 1, .125];
%! assert(all (abs (pow2 (x) - v) < sqrt (eps)));

%!test
%! x = [3, 0, -3, 4, 0, -4, 5, 0, -5];
%! y = [-2, -2, -2, 1, 1, 1, 3, 3, 3];
%! z = x .* (2 .^ y);
%! assert(all (abs (pow2 (x,y) - z) < sqrt (eps)));

%!error pow2();