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 routineThis 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
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cubic.patch
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