/usr/share/octave/packages/statistics-1.2.4/expstat.m is in octave-statistics 1.2.4-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 | ## 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}] =} expstat (@var{l})
## Compute mean and variance of the exponential distribution.
##
## @subheading Arguments
##
## @itemize @bullet
## @item
## @var{l} is the parameter of the exponential distribution. The
## elements of @var{l} must be positive
## @end itemize
##
## @subheading Return values
##
## @itemize @bullet
## @item
## @var{m} is the mean of the exponential distribution
##
## @item
## @var{v} is the variance of the exponential distribution
## @end itemize
##
## @subheading Example
##
## @example
## @group
## l = 1:6;
## [m, v] = expstat (l)
## @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 exponential distribution
function [m, v] = expstat (l)
# Check arguments
if (nargin != 1)
print_usage ();
endif
if (! isempty (l) && ! ismatrix (l))
error ("expstat: l must be a numeric matrix");
endif
# Calculate moments
m = l;
v = m .^ 2;
# Continue argument check
k = find (! (l > 0) | ! (l < Inf));
if (any (k))
m(k) = NaN;
v(k) = NaN;
endif
endfunction
%!test
%! l = 1:6;
%! [m, v] = expstat (l);
%! assert (m, [1, 2, 3, 4, 5, 6], 0.001);
%! assert (v, [1, 4, 9, 16, 25, 36], 0.001);
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