1 ## Copyright (C) 2012 Rik Wehbring
2 ## Copyright (C) 1995-2012 Kurt Hornik
4 ## This file is part of Octave.
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.
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.
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/>.
21 ## @deftypefn {Function File} {} laplace_rnd (@var{r})
22 ## @deftypefnx {Function File} {} laplace_rnd (@var{r}, @var{c}, @dots{})
23 ## @deftypefnx {Function File} {} laplace_rnd ([@var{sz}])
24 ## Return a matrix of random samples from the Laplace distribution.
26 ## When called with a single size argument, return a square matrix with
27 ## the dimension specified. When called with more than one scalar argument the
28 ## first two arguments are taken as the number of rows and columns and any
29 ## further arguments specify additional matrix dimensions. The size may also
30 ## be specified with a vector of dimensions @var{sz}.
33 ## Author: KH <Kurt.Hornik@wu-wien.ac.at>
34 ## Description: Random deviates from the Laplace distribution
36 function rnd = laplace_rnd (varargin)
43 if (isscalar (varargin{1}) && varargin{1} >= 0)
44 sz = [varargin{1}, varargin{1}];
45 elseif (isrow (varargin{1}) && all (varargin{1} >= 0))
48 error ("laplace_rnd: dimension vector must be row vector of non-negative integers");
51 if (any (cellfun (@(x) (!isscalar (x) || x < 0), varargin)))
52 error ("laplace_rnd: dimensions must be non-negative integers");
58 rnd = (tmp < 1/2) .* log (2 * tmp) - (tmp > 1/2) .* log (2 * (1 - tmp));
63 %!assert(size (laplace_rnd (3)), [3, 3]);
64 %!assert(size (laplace_rnd ([4 1])), [4, 1]);
65 %!assert(size (laplace_rnd (4,1)), [4, 1]);
67 %% Test input validation
68 %!error laplace_rnd ()
69 %!error laplace_rnd (-1)
70 %!error laplace_rnd (ones(2))
71 %!error laplace_rnd ([2 -1 2])
72 %!error laplace_rnd (1, ones(2))
73 %!error laplace_rnd (1, -1)