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Re: Same .m file: different results with different versions of Octave


From: Judd Storrs
Subject: Re: Same .m file: different results with different versions of Octave
Date: Sat, 17 Apr 2010 11:59:33 -0400

I suspect you are correct that tanh seems to be broken in octave. What
I see is that the Z() function is always returning NaN and the NaN
come from the tanh(). The problem can be reproduced with octave I have
on my machine (Octave 3.0.5, 3.2.3, 3.3.51+, Ubuntu 9.10 64-bit)

> tanh(50000+50000i)
NaN

But in Matlab:

> tanh(50000+50000i)
1

I suspect that you're seeing differences in the C math libraries
between the machines. This may be a bug in libc related to these
(supposedly fixed) bugs from 2005:

http://lists.debian.org/debian-glibc/2005/09/msg00097.html
https://bugzilla.redhat.com/show_bug.cgi?id=160759

FWIW the sample code testing libc fails on my machine. Perhaps it's
time to file a bug report.


--judd


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