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Re: More /.{I->-1} craziness

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  • Subject: [mg106434] Re: More /.{I->-1} craziness
  • From: Bill Rowe <readnews at>
  • Date: Tue, 12 Jan 2010 04:50:37 -0500 (EST)

On 1/11/10 at 5:27 AM, fateman at (Richard Fateman)

>Bill Rowe wrote:

>>Reporting a behavior that works as designed as a bug and hoping it
>>will be "fixed" seems very unproductive to me.

>When one first reports a behavior that one believes is a bug, the
>natural hope is that it will be fixed.

Which is very reasonably when what is reported as a bug is
indeed a bug. But it is not reasonable to expect something
reported as a bug to be changed when it is not a bug. Nor is it
reasonable to expect WRI to intuit your meaning of bug when it
differs from the standard accepted difference. That is, the
behavior being discussed is simply not a bug. It is exactly the
behavior the documentation indicates should occur.

>>But it is highly desirable new versions of Mathematica run code
>>written for earlier versions.

>Of course, but that is not enforced by WRI. Why should you enforce

What??? I have no access to the source code. And if I have any
significant influence over WRI, I am not aware of it. In short,
I've no capability to enforce my view of how Mathematica should
be designed on anyone.

>Your view would make it impossible to improve anything e.g. new
>integration results, which would be incompatible with previous
>versions, which might (for example) depend on certainly integration
>problems NOT being done by the Integrate program.

Let me just respond here by clearly stating the above is not
representative of my view at all.

>>Altering design decisions almost certainly means the new version
>>will not run some code written for earlier versions.

>Not necessarily. Sometimes the change will return all results that
>were previously computed, but will provide functionality over a new
>domain too, as Integrate.

That type of change sounds more like a change in the method of
computation not a change of design.

>>I don't believe the existence of users who have not yet taken the
>>time to understand the current design is sufficient cause to change
>>the current design.

>Again, you insist that I am proposing changing the current design.
>1. I think the current design is wrong. (or woefully
>underdocumented) 2. I think a better facility can be designed and

You clearly state here you think the design "is wrong" and can
be better. If you are not suggesting changing the design what
are you suggesting? Leaving a design you feel is incorrect and
somehow patching it?

>>But on this second point, I am not the one who needs to be
>>convinced. It is someone at WRI who could actually implement a
>>change and their management.

>I disagree.

Well if you think *I* am the one who needs convincing your
prospects for seeing this change are very slim indeed.

>All you have to do is use your experience, skill, and imagination, to
>think about what a GOOD substitution facility should do as to not
>confuse someone who merely knows mathematics, and does not have an
>interest in learning the subtleties of FullForm, Reduce, Eliminate,
>....  Your ideas could then be implemented in a newly designed
>additional facility.

You appear to be suggesting Mathematica should be written to
enable someone to do mathematics without understanding much in
the way in which Mathematica works. While I can there are those
who want something to just work without additional effort on
their part, I don't see this as happening with anything as
powerful and complex as Mathematica. Someone who "merely knows"
mathematics and has no interest in FullForm, Reduce, Eliminate,
ReplacementRule etc would be well advised to do mathematics by
hand and not use Mathematica at all. It simply is not reasonable
to expect good results from a tool if you are unwilling to learn
how to use the tool.

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