update packages

[CreaPhase.git] / octave_packages / m / statistics / distributions / geoinv.m

diff --git a/octave_packages/m/statistics/distributions/geoinv.m b/octave_packages/m/statistics/distributions/geoinv.m
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+## 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} {} geoinv (@var{x}, @var{p})
+## For each element of @var{x}, compute the quantile (the inverse of
+## the CDF) at @var{x} of the geometric distribution with parameter @var{p}.
+## @end deftypefn
+
+## Author: KH <Kurt.Hornik@wu-wien.ac.at>
+## Description: Quantile function of the geometric distribution
+
+function inv = geoinv (x, p)
+
+  if (nargin != 2)
+    print_usage ();
+  endif
+
+  if (!isscalar (p))
+    [retval, x, p] = common_size (x, p);
+    if (retval > 0)
+      error ("geoinv: X and P must be of common size or scalars");
+    endif
+  endif
+
+  if (iscomplex (x) || iscomplex (p))
+    error ("geoinv: X and P must not be complex");
+  endif
+
+  if (isa (x, "single") || isa (p, "single"))
+    inv = NaN (size (x), "single");
+  else
+    inv = NaN (size (x));
+  endif
+
+  k = (x == 1) & (p >= 0) & (p <= 1);
+  inv(k) = Inf;
+
+  k = (x >= 0) & (x < 1) & (p > 0) & (p <= 1);
+  if (isscalar (p))
+    inv(k) = max (ceil (log (1 - x(k)) / log (1 - p)) - 1, 0);
+  else
+    inv(k) = max (ceil (log (1 - x(k)) ./ log (1 - p(k))) - 1, 0);
+  endif
+
+endfunction
+
+
+%!shared x
+%! x = [-1 0 0.75 1 2];
+%!assert(geoinv (x, 0.5*ones(1,5)), [NaN 0 1 Inf NaN]);
+%!assert(geoinv (x, 0.5), [NaN 0 1 Inf NaN]);
+%!assert(geoinv (x, 0.5*[1 -1 NaN 4 1]), [NaN NaN NaN NaN NaN]);
+%!assert(geoinv ([x(1:2) NaN x(4:5)], 0.5), [NaN 0 NaN Inf NaN]);
+
+%% Test class of input preserved
+%!assert(geoinv ([x, NaN], 0.5), [NaN 0 1 Inf NaN NaN]);
+%!assert(geoinv (single([x, NaN]), 0.5), single([NaN 0 1 Inf NaN NaN]));
+%!assert(geoinv ([x, NaN], single(0.5)), single([NaN 0 1 Inf NaN NaN]));
+
+%% Test input validation
+%!error geoinv ()
+%!error geoinv (1)
+%!error geoinv (1,2,3)
+%!error geoinv (ones(3),ones(2))
+%!error geoinv (ones(2),ones(3))
+%!error geoinv (i, 2)
+%!error geoinv (2, i)
+