--- /dev/null
+## Copyright (C) 2012 Rik Wehbring
+## Copyright (C) 1997-2012 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} {} hygeinv (@var{x}, @var{t}, @var{m}, @var{n})
+## For each element of @var{x}, compute the quantile (the inverse of
+## the CDF) at @var{x} of the hypergeometric distribution with parameters
+## @var{t}, @var{m}, and @var{n}. This is the probability of obtaining @var{x}
+## marked items when randomly drawing a sample of size @var{n} without
+## replacement from a population of total size @var{t} containing @var{m}
+## marked items.
+##
+## The parameters @var{t}, @var{m}, and @var{n} must be positive integers
+## with @var{m} and @var{n} not greater than @var{t}.
+## @end deftypefn
+
+## Author: KH <Kurt.Hornik@wu-wien.ac.at>
+## Description: Random deviates from the hypergeometric distribution
+
+function inv = hygeinv (x, t, m, n)
+
+ if (nargin != 4)
+ print_usage ();
+ endif
+
+ if (!isscalar (t) || !isscalar (m) || !isscalar (n))
+ [retval, x, t, m, n] = common_size (x, t, m, n);
+ if (retval > 0)
+ error ("hygeinv: X, T, M, and N must be of common size or scalars");
+ endif
+ endif
+
+ if (iscomplex (x) || iscomplex (t) || iscomplex (m) || iscomplex (n))
+ error ("hygeinv: X, T, M, and N must not be complex");
+ endif
+
+ if (isa (x, "single") || isa (t, "single") || isa (m, "single") || isa (n, "single"))
+ inv = NaN (size (x), "single");
+ else
+ inv = NaN (size (x));
+ endif
+
+ ok = ((t >= 0) & (m >= 0) & (n > 0) & (m <= t) & (n <= t) &
+ (t == fix (t)) & (m == fix (m)) & (n == fix (n)));
+
+ if (isscalar (t))
+ if (ok)
+ inv = discrete_inv (x, 0 : n, hygepdf (0 : n, t, m, n));
+ inv(x == 0) = 0; # Hack to return correct value for start of distribution
+ endif
+ else
+ for i = find (ok(:)') # Must be row vector arg to for loop
+ v = 0 : n(i);
+ if (x(i) == 0)
+ inv(i) = 0; # Hack to return correct value for start of distribution
+ else
+ inv(i) = discrete_inv (x(i), v, hygepdf (v, t(i), m(i), n(i)));
+ endif
+ endfor
+ endif
+
+endfunction
+
+
+%!shared x
+%! x = [-1 0 0.5 1 2];
+%!assert(hygeinv (x, 4*ones(1,5), 2*ones(1,5), 2*ones(1,5)), [NaN 0 1 2 NaN]);
+%!assert(hygeinv (x, 4*ones(1,5), 2, 2), [NaN 0 1 2 NaN]);
+%!assert(hygeinv (x, 4, 2*ones(1,5), 2), [NaN 0 1 2 NaN]);
+%!assert(hygeinv (x, 4, 2, 2*ones(1,5)), [NaN 0 1 2 NaN]);
+%!assert(hygeinv (x, 4*[1 -1 NaN 1.1 1], 2, 2), [NaN NaN NaN NaN NaN]);
+%!assert(hygeinv (x, 4, 2*[1 -1 NaN 1.1 1], 2), [NaN NaN NaN NaN NaN]);
+%!assert(hygeinv (x, 4, 5, 2), [NaN NaN NaN NaN NaN]);
+%!assert(hygeinv (x, 4, 2, 2*[1 -1 NaN 1.1 1]), [NaN NaN NaN NaN NaN]);
+%!assert(hygeinv (x, 4, 2, 5), [NaN NaN NaN NaN NaN]);
+%!assert(hygeinv ([x(1:2) NaN x(4:5)], 4, 2, 2), [NaN 0 NaN 2 NaN]);
+
+%% Test class of input preserved
+%!assert(hygeinv ([x, NaN], 4, 2, 2), [NaN 0 1 2 NaN NaN]);
+%!assert(hygeinv (single([x, NaN]), 4, 2, 2), single([NaN 0 1 2 NaN NaN]));
+%!assert(hygeinv ([x, NaN], single(4), 2, 2), single([NaN 0 1 2 NaN NaN]));
+%!assert(hygeinv ([x, NaN], 4, single(2), 2), single([NaN 0 1 2 NaN NaN]));
+%!assert(hygeinv ([x, NaN], 4, 2, single(2)), single([NaN 0 1 2 NaN NaN]));
+
+%% Test input validation
+%!error hygeinv ()
+%!error hygeinv (1)
+%!error hygeinv (1,2)
+%!error hygeinv (1,2,3)
+%!error hygeinv (1,2,3,4,5)
+%!error hygeinv (ones(2), ones(3), 1, 1)
+%!error hygeinv (1, ones(2), ones(3), 1)
+%!error hygeinv (1, 1, ones(2), ones(3))
+%!error hygeinv (i, 2, 2, 2)
+%!error hygeinv (2, i, 2, 2)
+%!error hygeinv (2, 2, i, 2)
+%!error hygeinv (2, 2, 2, i)
+