/octave-3.6.2/scripts/statistics/distributions/poissrnd.m
Objective C | 122 lines | 106 code | 16 blank | 0 comment | 18 complexity | 4d07a4941adc2951e5d4477de62af4ae MD5 | raw file
Possible License(s): GPL-3.0
1## Copyright (C) 2012 Rik Wehbring
2## Copyright (C) 1995-2012 Kurt Hornik
3##
4## This file is part of Octave.
5##
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.
10##
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.
15##
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/>.
19
20## -*- texinfo -*-
21## @deftypefn {Function File} {} poissrnd (@var{lambda})
22## @deftypefnx {Function File} {} poissrnd (@var{lambda}, @var{r})
23## @deftypefnx {Function File} {} poissrnd (@var{lambda}, @var{r}, @var{c}, @dots{})
24## @deftypefnx {Function File} {} poissrnd (@var{lambda}, [@var{sz}])
25## Return a matrix of random samples from the Poisson distribution with
26## parameter @var{lambda}.
27##
28## When called with a single size argument, return a square matrix with
29## the dimension specified. When called with more than one scalar argument the
30## first two arguments are taken as the number of rows and columns and any
31## further arguments specify additional matrix dimensions. The size may also
32## be specified with a vector of dimensions @var{sz}.
33##
34## If no size arguments are given then the result matrix is the size of
35## @var{lambda}.
36## @end deftypefn
37
38## Author: KH <Kurt.Hornik@wu-wien.ac.at>
39## Description: Random deviates from the Poisson distribution
40
41function rnd = poissrnd (lambda, varargin)
42
43 if (nargin < 1)
44 print_usage ();
45 endif
46
47 if (nargin == 1)
48 sz = size (lambda);
49 elseif (nargin == 2)
50 if (isscalar (varargin{1}) && varargin{1} >= 0)
51 sz = [varargin{1}, varargin{1}];
52 elseif (isrow (varargin{1}) && all (varargin{1} >= 0))
53 sz = varargin{1};
54 else
55 error ("poissrnd: dimension vector must be row vector of non-negative integers");
56 endif
57 elseif (nargin > 2)
58 if (any (cellfun (@(x) (!isscalar (x) || x < 0), varargin)))
59 error ("poissrnd: dimensions must be non-negative integers");
60 endif
61 sz = [varargin{:}];
62 endif
63
64 if (!isscalar (lambda) && !isequal (size (lambda), sz))
65 error ("poissrnd: LAMBDA must be scalar or of size SZ");
66 endif
67
68 if (iscomplex (lambda))
69 error ("poissrnd: LAMBDA must not be complex");
70 endif
71
72 if (isa (lambda, "single"))
73 cls = "single";
74 else
75 cls = "double";
76 endif
77
78 if (isscalar (lambda))
79 if (lambda >= 0 && lambda < Inf)
80 rnd = randp (lambda, sz);
81 if (strcmp (cls, "single"))
82 rnd = single (rnd);
83 endif
84 else
85 rnd = NaN (sz, cls);
86 endif
87 else
88 rnd = NaN (sz, cls);
89
90 k = (lambda >= 0) & (lambda < Inf);
91 rnd(k) = randp (lambda(k));
92 endif
93
94endfunction
95
96%!assert(size (poissrnd (2)), [1, 1]);
97%!assert(size (poissrnd (ones(2,1))), [2, 1]);
98%!assert(size (poissrnd (ones(2,2))), [2, 2]);
99%!assert(size (poissrnd (1, 3)), [3, 3]);
100%!assert(size (poissrnd (1, [4 1])), [4, 1]);
101%!assert(size (poissrnd (1, 4, 1)), [4, 1]);
102
103%% Test class of input preserved
104%!assert(class (poissrnd (2)), "double");
105%!assert(class (poissrnd (single(2))), "single");
106%!assert(class (poissrnd (single([2 2]))), "single");
107
108%% Test input validation
109%!error poissrnd ()
110%!error poissrnd (1, -1)
111%!error poissrnd (1, ones(2))
112%!error poissrnd (1, 2, ones(2))
113%!error poissrnd (i)
114%!error poissrnd (1, 2, -1)
115%!error poissrnd (1, [2 -1 2])
116%!error poissrnd (ones(2,2), 3)
117%!error poissrnd (ones(2,2), [3, 2])
118%!error poissrnd (ones(2,2), 2, 3)
119
120%!assert (poissrnd (0, 1, 1), 0)
121%!assert (poissrnd ([0, 0, 0], [1, 3]), [0 0 0])
122