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.
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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} {} geopdf (@var{x}, @var{p})
22 ## For each element of @var{x}, compute the probability density function
23 ## (PDF) at @var{x} of the geometric distribution with parameter @var{p}.
26 ## Author: KH <Kurt.Hornik@wu-wien.ac.at>
27 ## Description: PDF of the geometric distribution
29 function pdf = geopdf (x, p)
36 [retval, x, p] = common_size (x, p);
38 error ("geopdf: X and P must be of common size or scalars");
42 if (iscomplex (x) || iscomplex (p))
43 error ("geopdf: X and P must not be complex");
46 if (isa (x, "single") || isa (p, "single"))
47 pdf = zeros (size (x), "single");
49 pdf = zeros (size (x));
52 k = isnan (x) | (x == Inf) | !(p >= 0) | !(p <= 1);
55 k = (x >= 0) & (x < Inf) & (x == fix (x)) & (p > 0) & (p <= 1);
57 pdf(k) = p * ((1 - p) .^ x(k));
59 pdf(k) = p(k) .* ((1 - p(k)) .^ x(k));
67 %! y = [0, 1/2, 1/4, NaN];
68 %!assert(geopdf (x, 0.5*ones(1,4)), y);
69 %!assert(geopdf (x, 0.5), y);
70 %!assert(geopdf (x, 0.5*[-1 NaN 4 1]), [NaN NaN NaN y(4)]);
71 %!assert(geopdf ([x, NaN], 0.5), [y, NaN]);
73 %% Test class of input preserved
74 %!assert(geopdf (single([x, NaN]), 0.5), single([y, NaN]), 5*eps("single"));
75 %!assert(geopdf ([x, NaN], single(0.5)), single([y, NaN]), 5*eps("single"));
77 %% Test input validation
80 %!error geopdf (1,2,3)
81 %!error geopdf (ones(3),ones(2))
82 %!error geopdf (ones(2),ones(3))