Re: Abs and Sign anomolies
- To: mathgroup at smc.vnet.net
- Subject: [mg7411] Re: Abs and Sign anomolies
- From: hans.steffani at e-technik.tu-chemnitz.de (Hans Steffani)
- Date: Sat, 31 May 1997 15:07:19 -0400 (EDT)
- Organization: University of Technology Chemnitz, FRG
- Sender: owner-wri-mathgroup at wolfram.com
Jack Goldberg <jackgold at math.lsa.umich.edu> writes:
My system delivers:
In Abs[Sign[x]] // Simplify
>which is wrong if x = 0. For, Sign = 0 and Abs = 0. So that the
>output of Abs[Sign[x]] should be unsimplified. Indeed, Mma returns
> Abs[Sign] = 0
>Although multiple crashes (hard and soft) and exporting graphics are
>extremely annoying, a mathematical "bug" is a far more serious problem.
>A programming error like this can lead to disaster and I urge the
>newsgroup to post all such anomalies as soon as they are discovered. We
>cannot assume that contacting Wolfram Research will result in a warning
>in their FAQ site, nor a timely fix.
>Wouldn't it be nice if someone (other than Wolfram Research)) could keep
>track of all mathematical "bugs" much the way one of our people keep
>track of relative speeds of the kernel on different platforms? The
>advantages for all of us are so clear that no argument need be given.
>I would be willing to do this, but - I'm embarrasses to admit - I don't
>know how to set up a Web page or whatever so that people could access
>the complilations automatically! If anyone wishes to send me their
>discoveries I will be happy to confirm them and keep a list.
>University of Michigan
>Ann Arbor Michigan
>e-mail: jackgold at math.lsa.umich.edu
Hans Friedrich Steffani
Institut fuer Elektrische Maschinen und Antriebe, TU Chemnitz-Zwickau
mailto:hans.steffani at e-technik.tu-chemnitz.de
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