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.
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18 ## <http://www.gnu.org/licenses/>.
21 ## @deftypefn {Function File} {} poisscdf (@var{x}, @var{lambda})
22 ## For each element of @var{x}, compute the cumulative distribution
23 ## function (CDF) at @var{x} of the Poisson distribution with parameter
27 ## Author: KH <Kurt.Hornik@wu-wien.ac.at>
28 ## Description: CDF of the Poisson distribution
30 function cdf = poisscdf (x, lambda)
36 if (!isscalar (lambda))
37 [retval, x, lambda] = common_size (x, lambda);
39 error ("poisscdf: X and LAMBDA must be of common size or scalars");
43 if (iscomplex (x) || iscomplex (lambda))
44 error ("poisscdf: X and LAMBDA must not be complex");
47 if (isa (x, "single") || isa (lambda, "single"))
48 cdf = zeros (size (x), "single");
50 cdf = zeros (size (x));
53 k = isnan (x) | !(lambda > 0);
56 k = (x == Inf) & (lambda > 0);
59 k = (x >= 0) & (x < Inf) & (lambda > 0);
60 if (isscalar (lambda))
61 cdf(k) = 1 - gammainc (lambda, floor (x(k)) + 1);
63 cdf(k) = 1 - gammainc (lambda(k), floor (x(k)) + 1);
70 %! x = [-1 0 1 2 Inf];
71 %! y = [0, gammainc(1, (x(2:4) +1), 'upper'), 1];
72 %!assert(poisscdf (x, ones(1,5)), y);
73 %!assert(poisscdf (x, 1), y);
74 %!assert(poisscdf (x, [1 0 NaN 1 1]), [y(1) NaN NaN y(4:5)]);
75 %!assert(poisscdf ([x(1:2) NaN Inf x(5)], 1), [y(1:2) NaN 1 y(5)]);
77 %% Test class of input preserved
78 %!assert(poisscdf ([x, NaN], 1), [y, NaN]);
79 %!assert(poisscdf (single([x, NaN]), 1), single([y, NaN]), eps("single"));
80 %!assert(poisscdf ([x, NaN], single(1)), single([y, NaN]), eps("single"));
82 %% Test input validation
85 %!error poisscdf (1,2,3)
86 %!error poisscdf (ones(3),ones(2))
87 %!error poisscdf (ones(2),ones(3))
88 %!error poisscdf (i, 2)
89 %!error poisscdf (2, i)