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[Bug-gsl] [bug #42219] Division by zero in "gnewton" when "f" and "fdf"
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From: |
Patrick Alken |
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Subject: |
[Bug-gsl] [bug #42219] Division by zero in "gnewton" when "f" and "fdf" differ |
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Date: |
Mon, 28 Apr 2014 16:10:42 +0000 |
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User-agent: |
Mozilla/5.0 (X11; Linux i686 on x86_64; rv:28.0) Gecko/20100101 Firefox/28.0 |
Follow-up Comment #1, bug #42219 (project gsl):
The problem seems to be in this line of gnewton_set() in
multiroots/gnewton.c:
122 state->phi = enorm(f);
In the example program, the initial guess x is the solution vector, so the
F_DF call provides a vector f = 0.
Then in the first gnewton_iterate() call, on line
177 double theta = phi1 / phi0;
we divide by 0.
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