1 ## Copyright (C) 2006, 2007 Arno Onken <asnelt@asnelt.org>
3 ## This program is free software; you can redistribute it and/or modify it under
4 ## the terms of the GNU General Public License as published by the Free Software
5 ## Foundation; either version 3 of the License, or (at your option) any later
8 ## This program is distributed in the hope that it will be useful, but WITHOUT
9 ## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 ## FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
13 ## You should have received a copy of the GNU General Public License along with
14 ## this program; if not, see <http://www.gnu.org/licenses/>.
17 ## @deftypefn {Function File} {[@var{m}, @var{v}] =} expstat (@var{l})
18 ## Compute mean and variance of the exponential distribution.
20 ## @subheading Arguments
24 ## @var{l} is the parameter of the exponential distribution. The
25 ## elements of @var{l} must be positive
28 ## @subheading Return values
32 ## @var{m} is the mean of the exponential distribution
35 ## @var{v} is the variance of the exponential distribution
38 ## @subheading Example
43 ## [m, v] = expstat (l)
47 ## @subheading References
51 ## Wendy L. Martinez and Angel R. Martinez. @cite{Computational Statistics
52 ## Handbook with MATLAB}. Appendix E, pages 547-557, Chapman & Hall/CRC,
56 ## Athanasios Papoulis. @cite{Probability, Random Variables, and Stochastic
57 ## Processes}. McGraw-Hill, New York, second edition, 1984.
61 ## Author: Arno Onken <asnelt@asnelt.org>
62 ## Description: Moments of the exponential distribution
64 function [m, v] = expstat (l)
71 if (! isempty (l) && ! ismatrix (l))
72 error ("expstat: l must be a numeric matrix");
79 # Continue argument check
80 k = find (! (l > 0) | ! (l < Inf));
90 %! [m, v] = expstat (l);
91 %! assert (m, [1, 2, 3, 4, 5, 6], 0.001);
92 %! assert (v, [1, 4, 9, 16, 25, 36], 0.001);