--- /dev/null
+## Copyright (C) 2012 Rik Wehbring
+## Copyright (C) 1995-2012 Kurt Hornik
+##
+## This file is part of Octave.
+##
+## Octave is free software; you can redistribute it and/or modify it
+## under the terms of the GNU General Public License as published by
+## the Free Software Foundation; either version 3 of the License, or (at
+## your option) any later version.
+##
+## Octave is distributed in the hope that it will be useful, but
+## WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+## General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with Octave; see the file COPYING. If not, see
+## <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {} geocdf (@var{x}, @var{p})
+## For each element of @var{x}, compute the cumulative distribution function
+## (CDF) at @var{x} of the geometric distribution with parameter @var{p}.
+## @end deftypefn
+
+## Author: KH <Kurt.Hornik@wu-wien.ac.at>
+## Description: CDF of the geometric distribution
+
+function cdf = geocdf (x, p)
+
+ if (nargin != 2)
+ print_usage ();
+ endif
+
+ if (!isscalar (p))
+ [retval, x, p] = common_size (x, p);
+ if (retval > 0)
+ error ("geocdf: X and P must be of common size or scalars");
+ endif
+ endif
+
+ if (iscomplex (x) || iscomplex (p))
+ error ("geocdf: X and P must not be complex");
+ endif
+
+ if (isa (x, "single") || isa (p, "single"))
+ cdf = zeros (size (x), "single");
+ else
+ cdf = zeros (size (x));
+ endif
+
+ k = isnan (x) | !(p >= 0) | !(p <= 1);
+ cdf(k) = NaN;
+
+ k = (x == Inf) & (p >= 0) & (p <= 1);
+ cdf(k) = 1;
+
+ k = (x >= 0) & (x < Inf) & (x == fix (x)) & (p > 0) & (p <= 1);
+ if (isscalar (p))
+ cdf(k) = 1 - ((1 - p) .^ (x(k) + 1));
+ else
+ cdf(k) = 1 - ((1 - p(k)) .^ (x(k) + 1));
+ endif
+
+endfunction
+
+
+%!shared x,y
+%! x = [-1 0 1 Inf];
+%! y = [0 0.5 0.75 1];
+%!assert(geocdf (x, 0.5*ones(1,4)), y);
+%!assert(geocdf (x, 0.5), y);
+%!assert(geocdf (x, 0.5*[-1 NaN 4 1]), [NaN NaN NaN y(4)]);
+%!assert(geocdf ([x(1:2) NaN x(4)], 0.5), [y(1:2) NaN y(4)]);
+
+%% Test class of input preserved
+%!assert(geocdf ([x, NaN], 0.5), [y, NaN]);
+%!assert(geocdf (single([x, NaN]), 0.5), single([y, NaN]));
+%!assert(geocdf ([x, NaN], single(0.5)), single([y, NaN]));
+
+%% Test input validation
+%!error geocdf ()
+%!error geocdf (1)
+%!error geocdf (1,2,3)
+%!error geocdf (ones(3),ones(2))
+%!error geocdf (ones(2),ones(3))
+%!error geocdf (i, 2)
+%!error geocdf (2, i)
+