Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / statistics-1.1.3 / geostat.m

diff --git a/octave_packages/statistics-1.1.3/geostat.m b/octave_packages/statistics-1.1.3/geostat.m
new file mode 100644 (file)
index 0000000..a6c94a2
--- /dev/null
+++ b/octave_packages/statistics-1.1.3/geostat.m
@@ -0,0 +1,93 @@
+## Copyright (C) 2006, 2007 Arno Onken <asnelt@asnelt.org>
+##
+## This program 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.
+##
+## This program 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
+## this program; if not, see <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {[@var{m}, @var{v}] =} geostat (@var{p})
+## Compute mean and variance of the geometric distribution.
+##
+## @subheading Arguments
+##
+## @itemize @bullet
+## @item
+## @var{p} is the rate parameter of the geometric distribution. The
+## elements of @var{p} must be probabilities
+## @end itemize
+##
+## @subheading Return values
+##
+## @itemize @bullet
+## @item
+## @var{m} is the mean of the geometric distribution
+##
+## @item
+## @var{v} is the variance of the geometric distribution
+## @end itemize
+##
+## @subheading Example
+##
+## @example
+## @group
+## p = 1 ./ (1:6);
+## [m, v] = geostat (p)
+## @end group
+## @end example
+##
+## @subheading References
+##
+## @enumerate
+## @item
+## Wendy L. Martinez and Angel R. Martinez. @cite{Computational Statistics
+## Handbook with MATLAB}. Appendix E, pages 547-557, Chapman & Hall/CRC,
+## 2001.
+##
+## @item
+## Athanasios Papoulis. @cite{Probability, Random Variables, and Stochastic
+## Processes}. McGraw-Hill, New York, second edition, 1984.
+## @end enumerate
+## @end deftypefn
+
+## Author: Arno Onken <asnelt@asnelt.org>
+## Description: Moments of the geometric distribution
+
+function [m, v] = geostat (p)
+
+  # Check arguments
+  if (nargin != 1)
+    print_usage ();
+  endif
+
+  if (! isempty (p) && ! ismatrix (p))
+    error ("geostat: p must be a numeric matrix");
+  endif
+
+  # Calculate moments
+  q = 1 - p;
+  m = q ./ p;
+  v = q ./ (p .^ 2);
+
+  # Continue argument check
+  k = find (! (p >= 0) | ! (p <= 1));
+  if (any (k))
+    m(k) = NaN;
+    v(k) = NaN;
+  endif
+
+endfunction
+
+%!test
+%! p = 1 ./ (1:6);
+%! [m, v] = geostat (p);
+%! assert (m, [0, 1, 2, 3, 4, 5], 0.001);
+%! assert (v, [0, 2, 6, 12, 20, 30], 0.001);