/usr/share/octave/packages/3.2/optim-1.0.17/gjp.m is in octave-optim 1.0.17-1.
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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 | %% Copyright (C) 2010, 2011 Olaf Till
%%
%% 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 2 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, write to the Free Software
%% Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301USA
function m = gjp (m, k, l)
%% m = gjp (m, k[, l])
%%
%% m: matrix; k, l: row- and column-index of pivot, l defaults to k.
%%
%% Gauss-Jordon pivot as defined in Bard, Y.: Nonlinear Parameter
%% Estimation, p. 296, Academic Press, New York and London 1974. In
%% the pivot column, this seems not quite the same as the usual
%% Gauss-Jordan(-Clasen) pivot. Bard gives Beaton, A. E., 'The use of
%% special matrix operators in statistical calculus' Research Bulletin
%% RB-64-51 (1964), Educational Testing Service, Princeton, New Jersey
%% as a reference, but this article is not easily accessible. Another
%% reference, whose definition of gjp differs from Bards by some
%% signs, is Clarke, R. B., 'Algorithm AS 178: The Gauss-Jordan sweep
%% operator with detection of collinearity', Journal of the Royal
%% Statistical Society, Series C (Applied Statistics) (1982), 31(2),
%% 166--168.
if (nargin < 3)
l = k;
end
p = m(k, l);
if (p == 0)
error ('pivot is zero');
end
%% This is a case where I really hate to remain Matlab compatible,
%% giving so many indices twice.
m(k, [1:l-1, l+1:end]) = m(k, [1:l-1, l+1:end]) / p; % pivot row
m([1:k-1, k+1:end], [1:l-1, l+1:end]) = ... % except pivot row and col
m([1:k-1, k+1:end], [1:l-1, l+1:end]) - ...
m([1:k-1, k+1:end], l) * m(k, [1:l-1, l+1:end]);
m([1:k-1, k+1:end], l) = - m([1:k-1, k+1:end], l) / p; % pivot column
m(k, l) = 1 / p;
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