1 ## Copyright (C) 2008-2012 David Bateman
3 ## This file is part of Octave.
5 ## Octave is free software; you can redistribute it and/or modify it
6 ## under the terms of the GNU General Public License as published by
7 ## the Free Software Foundation; either version 3 of the License, or (at
8 ## your option) any later version.
10 ## Octave is distributed in the hope that it will be useful, but
11 ## WITHOUT ANY WARRANTY; without even the implied warranty of
12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 ## General Public License for more details.
15 ## You should have received a copy of the GNU General Public License
16 ## along with Octave; see the file COPYING. If not, see
17 ## <http://www.gnu.org/licenses/>.
20 ## @deftypefn {Function File} {} reallog (@var{x})
21 ## Return the real-valued natural logarithm of each element of @var{x}. Report
22 ## an error if any element results in a complex return value.
23 ## @seealso{log, realpow, realsqrt}
26 function y = reallog (x)
29 elseif (iscomplex (x) || any (x(:) < 0))
30 error ("reallog: produced complex result");
36 %!assert (log(1:5),reallog(1:5))
39 %! assert (log(x),reallog(x))