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annotate scripts/specfun/reallog.m @ 7621:4682dda22527

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Add the reallog, realsqrt and realpow functions
author David Bateman <dbateman@free.fr>
date Fri, 21 Mar 2008 16:09:01 +0100
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children 3eb2094eefe5
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7621
4682dda22527 Add the reallog, realsqrt and realpow functions
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1 ## Copyright (C) 2008 David Bateman
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2 ##
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3 ## This file is part of Octave.
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4 ##
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5 ## Octave is free software; you can redistribute it and/or modify it
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6 ## under the terms of the GNU General Public License as published by
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7 ## the Free Software Foundation; either version 3 of the License, or (at
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8 ## your option) any later version.
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9 ##
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10 ## Octave is distributed in the hope that it will be useful, but
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11 ## WITHOUT ANY WARRANTY; without even the implied warranty of
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12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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13 ## General Public License for more details.
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14 ##
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15 ## You should have received a copy of the GNU General Public License
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16 ## along with Octave; see the file COPYING. If not, see
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17 ## <http://www.gnu.org/licenses/>.
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18
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19 ## -*- texinfo -*-
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20 ## @deftypefn {Function File} {} realsqrt (@var{x})
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21 ## Return the real natural logarithm of @var{x}. If any element results in the
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22 ## return value being complex @code{reallog} produces an error.
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23 ## @seealso{log, realsqrt, realpow}
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24 ## @end deftypefn
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25
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26 function y = reallog (x)
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27 if (nargin != 1)
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28 print_usage ();
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29 elseif (iscomplex (x) || any (x(:) < 0))
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30 error ("reallog: produced complex result");
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31 else
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32 y = log (x);
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33 endif
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34 endfunction
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35
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36 %!assert (log(1:5),reallog(1:5))
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37 %!test
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38 %! x = rand (10,10);
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39 %! assert (log(x),reallog(x))
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40 %!error (reallog(-1))