[Octave-bug-tracker] [bug #36211] bug: crashes and endless loops

[anonymous]

Follow-up Comment #2, bug #36211 (project octave):

Hello, thanks for investigating this issue,

I'm using the "i686-pc-mingw32" version of 3.6.1.

yes, I know my statements are somewhat nonsensical :) - I just wanted to
create a tiny example. As far as I can see, the loop (or crash) occurs on
(every?) equation systems where the matrix contains any Inf value. 
I was doing curve fitting with a Gauss-Newton like algorithm (see below) that
did not converge, so that after a few iterations there where Inf values in the
equation system.


F = f(X,a);   % F: function values
              % a: vector of parameters
              % X,Y: Nx1-matrices with measurement data (N is about 20000)
r = F-Y;      % residuals
J = jac(X,a); % jac: function that forms jacobi-matrix

% (here I should check if there are Inf values in J ...)

s = J  r;    % crash...
a -= s;
% (...iterate until algorithm converges...)


It seems that if the Inf value is in the first column, then it crashes (or on
linux: shows the expected error message). If the Inf is in a column >1 then it
is doing it's endless loop.

Regards
Stefan Reiser


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