Karim BELABAS on Fri, 12 Sep 2003 01:57:00 +0200 (MEST)

[Date Prev] [Date Next] [Thread Prev] [Thread Next] [Date Index] [Thread Index]

Re: Bug report about GMP Kernel

On Tue, 9 Sep 2003, Franck MICHEL wrote:
> I'm doing computations with series of floating point complex coefficients,
> 4500 digits. I've installed Pari 2.2.6 with GMP Kernel and I'm very
> satisfied by its  speed (about 3 times faster than Pari 2.1.0)
> With simple programs, all works fine.
> But with more complicated programs, the values obtained are wrong.
> Unfortunately, I wasn't able to identify a simple operation (division,
> power...) generating a false result. Therefore, I've simply shortened a
> program to keep the first wrong result obtained.
> The program uses relatively large data files in input, so I preferred to
> use a web page for the bug report, rather than to send it by mail.

The input data files were _read_ incorrectly, due to an unforeseen memory
corruption problem [ due to inputs with many leading zeroes ]. The GMP kernel
uses a little more memory and was more likely to be affected.

Fixed in CVS.



P.S: better than affiche(), try 'precision(x, 9)' [ for some large float x ]
Karim Belabas                     Tel: (+33) (0)1 69 15 57 48
Dép. de Mathématiques, Bât. 425   Fax: (+33) (0)1 69 15 60 19
Université Paris-Sud              http://www.math.u-psud.fr/~belabas/
F-91405 Orsay (France)            http://www.parigp-home.de/  [PARI/GP]