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From: barry@pico.math.ucla.edu (Barry Merriman)
Newsgroups: comp.sys.next
Subject: NeXT Mathematica Bug
Message-ID: <1991Mar3.053006.2986@math.ucla.edu>
Date: 3 Mar 91 05:30:06 GMT
Sender: news@math.ucla.edu
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Organization: UCLA Dept. of Math, UCLA Inst. for Fusion and Plasma Research
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I have found a nasty, basic bug in NeXT Mathematica
(Mathematica 1.2, running on a 2.0 Slab---but copied from
a 1.0a 030 cube, though).

The bug: Tanh[x] is not computed correctly. To _see_ if you have
it, do

Plot[Tanh[x],{x,-3,3}]

and see if there is an obvious discontinuity in the graph. Or,
do

Tanh[-1.8]

and see if you get a number < -1 (note Range of tanh is (-1,1)).

The consensus of the mathematica mailing list is that this bug is
a byproduct of the interaction between M'ma 1.2 and NeXTStep 2.0
(although one fellow claims the above crashes his SparcStation!?)
Hopefully it will be fixed in M'ma 2.0---since Wolfram is on
tour and will be at UCLA next week, I'll ask him :-).

However, if you write your own tanh[x] in terms of exponentials,
it works fine.

--
Barry Merriman
UCLA Dept. of Math
UCLA Inst. for Fusion and Plasma Research
barry@math.ucla.edu (Internet)