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[Bug-gsl] problem in cubic solver
From: |
Lorenzo Moneta |
Subject: |
[Bug-gsl] problem in cubic solver |
Date: |
Tue, 28 Apr 2009 17:11:31 +0200 |
Hello,
I have found a problem with solver for cubic equation (both complex
and real one)
In some particular case a NaN is returned, as shown in the attached
text example.
The problem is observed mainly on 64 bit architectures (for example
Linux 64-bit with gcc 4.3) and not on 32 bit architectures.
This is due to a problem in a sqrt. A patch is attached fixing the
problem for the complex routine (gsl_poly_complex_solve_cubic ).
A similar patch can be probably done also for the real routine
This patch fails the current test for polynomial in gsl, however in
my opinion, this is acceptable, because the test condition is too
strict. With a slight change of the test coefficient, you will have a
similar failure also with the current version.
Best Regards
Lorenzo Moneta
ROOT project (http://root.cern.ch )
CERN
test_cubic_gsl.c
Description: Binary data
cubic.patch
Description: Binary data
- [Bug-gsl] problem in cubic solver,
Lorenzo Moneta <=