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Re: Floating point exception when taking a reciprocal

  • To: mathgroup at smc.vnet.net
  • Subject: [mg110490] Re: Floating point exception when taking a reciprocal
  • From: Niels Walet <Niels.Walet at manchester.ac.uk>
  • Date: Mon, 21 Jun 2010 02:10:13 -0400 (EDT)

Leo Alekseyev wrote:
> I am running into a strange bug where taking reciprocals of a list of
> floating point numbers crashes the kernel with a floating point
> exception.  This is on a Linux x86_64 system, Ubuntu 9.10, running
> Mathematica 7.0.1.0
>
> Something like
>    foo=Array[1.0&,1000]; 1/foo
> or
>    foo=RandomReal/@Range[100]; 1/foo
> gives me the crash
> Replacing floats with integers makes things work fine, also, for small
> enough lists (order of 10 elements) everything works.
>
> Same version of Mathematica on a 32-bit linux system or on Windows
> doesn't exhibit this behavior.
>
> I am rather mystified by what's going on; my hardware/OS is pretty
> standard, so if the bug were this obvious it would have long been
> known by now...  But if anyone else has run into similar behavior
> and/or knows of some sort of a fix, please let me know.
>
> Thanks,
>
> --Leo
>
>   
I have seen similar problems (with Scientific linux 5 64 bits on an 
intel i5 processor). The same code works on the identical OS with an 
older Core2 processor. I have the feeling it is due to the issue with 
the intel math library for i7 
(http://support.wolfram.com/technotes/IntelCorei7.html), but am not 
sure, since I can't directly talk to wolfram (site license).

-- 
Prof. Niels R. Walet                    Phone:  +44(0)1613063693
School of Physics and Astronomy         Fax:    +44(0)1613064303
The University of Manchester            Mobile: +44(0)7905438934
Manchester, M60 1QD,  UK
Niels.Walet at manchester.ac.uk http://theory.phy.umist.ac.uk/~mccsnrw




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