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MathGroup Archive 2001

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Re: A bug of Integrate[] in Mathematica 4.1 (and 4.0)

  • To: mathgroup at smc.vnet.net
  • Subject: [mg27412] Re: A bug of Integrate[] in Mathematica 4.1 (and 4.0)
  • From: Hendrik van Hees <h.vanhees at gsi.de>
  • Date: Sun, 25 Feb 2001 00:53:35 -0500 (EST)
  • References: <972f8t$4ea@smc.vnet.net> <974vgh$6h1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Jens-Peer Kuska wrote:

> a) everyone that use a computer algebra and blind trust it's results
>    is a born fool

I might be a born fool but I'm never trusting CA systems in mathematical
results ;-).

> b) don't call it "bug", call it feature

Please call a bug a bug. I had a nice private discussion with someone
from Wolfram Res. who admitted now that it is a bug. I'm aware of the
fact that a fix of bugs of this kind is a rather complicated stuff.

> c) WRI cares about this features

Well, I was a little too naughty. I wanted also to say that I find
Mathematica a great tool, and it is impossible to get a multi purpose
CA-system without bugs. I was only complaining about some support team
emplyees who are telling me a bug is not a bug.

> d) a modification in Integrate[] needs probably a full new kernel

Fine. How about version 4.1? Could someone check the my simple example

Integrate[sqrt[(r-x)(r+x)],{x,-r,r}]


> g) when a sufficient number of features are corrected we get a version
>    x.y.1  typical for free -- just a e-mail to the sales department is
>    needed,  some days later a CD-ROM arrives you - can they do more ?

Ok, is there such a CD-ROM for the student version of version 4.0?

> h) I assume that a public list of known bugs would be bad publicity
>    because the most people believe that a software must be complete
>    bug free to work at all. Bad sales due to confused customers
>    ("What ? Mathematica has bugs ???" =:-O ) can't be in the interest
>    of any Mathematica user.

No, I think that the users of Mathematica are smart enough to like such
bug reports. It is only helpful to avoid trouble from the very
beginning. At the long sight it is a bad politics for a software company
to hide errors. Wolfram research has some bug lists, as I have learned
from my correspondence. It is not of my interest to make Mathematica
worse saled than now.

The behaviour you advertise for software companies might be the reason
that sometimes non-commercial software is more stable than commercial.
It is also very easy to communicate with open source software developers
because they have no interest in hiding bugs but in finding bugs and
cure them, and the best thing for a CA-system is to have bug reports
from real users of the system, applying it in their practical work.
Since Mathematica is so general there are a lot of different communities
using it for a lot of different task so that it is easy to find many
different kinds of bugs which again is a chance to fix them for the next
version.

But if I hear mathematically questionable arguments that a bug is not a
bug or, even worse, that a bug is a feature as you did above, I have not
much confidence that the bug will be fixed in a later version, because
arguing in this way prevents developing better algorithms.


-- 
Hendrik van Hees		Phone:  ++49 6159 71-2751
c/o GSI-Darmstadt SB3 3.183	Fax:    ++49 6159 71-2990
Planckstr. 1			mailto:h.vanhees at gsi.de
D-64291 Darmstadt		http://theory.gsi.de/~vanhees/index.html


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