update packages

[CreaPhase.git] / octave_packages / m / specfun / reallog.m

diff --git a/octave_packages/m/specfun/reallog.m b/octave_packages/m/specfun/reallog.m
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+## Copyright (C) 2008-2012 David Bateman
+##
+## This file is part of Octave.
+##
+## Octave is free software; you can redistribute it and/or modify it
+## 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.
+##
+## Octave is distributed in the hope that it will be useful, but
+## WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+## General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with Octave; see the file COPYING.  If not, see
+## <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {} reallog (@var{x})
+## Return the real-valued natural logarithm of each element of @var{x}.  Report
+## an error if any element results in a complex return value.
+## @seealso{log, realpow, realsqrt}
+## @end deftypefn
+
+function y = reallog (x)
+  if (nargin != 1)
+    print_usage ();
+  elseif (iscomplex (x) || any (x(:) < 0))
+    error ("reallog: produced complex result");
+  else
+    y = log (x);
+  endif
+endfunction
+
+%!assert (log(1:5),reallog(1:5))
+%!test
+%! x = rand (10,10);
+%! assert (log(x),reallog(x))
+%!error (reallog(-1))