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Re: A strange bug in Solve

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  • Subject: [mg24485] Re: [mg24354] A strange bug in Solve
  • From: mend0070 at (Philip C Mendelsohn)
  • Date: Wed, 19 Jul 2000 01:21:57 -0400 (EDT)
  • Organization: University of Minnesota, Twin Cities Campus
  • References: <8kjccd$> <ZU0d5.917$>
  • Sender: owner-wri-mathgroup at

Kevin J. McCann (kevinmccann at wrote:
: While using Simplify is all well and good, its use presupposes that you know
: what the answer is or that there is an answer. I have often seen posts on
: similar types of problems which suggest that if you just do this, this, and
: this to your problem then Mathematica will find the answer. This is NOT
: satisfactory. If Mathematica needs to simplify the input before it executes Solve,
: then it should do it. One should not be expected to know the answer before
: asking Mathematica for it.

I would respectfully submit that one should reasonably be expected to 
know something *about* the answer before giving it to M.

It would be too flippant to suggest that the extrapolation of your 
assertion is that M should be able to "do what one means, not what one

It is probably reasonable to program a routine to trap Solve errors and
try again using other algorithms, or other forms of the input, but M
does that to varying degrees already, if I understand things correctly.

It is almost trivial to try again after Simplifying (or massaging in 
a large number of ways,) and the number of input conditions so vast that
I suspect this is a conscious design choice:  to let it be implemented
by the user as they see fit.

I, for one, would be interested in any algorithm you or anyone else comes
up with for deciding on the appropriate form of input to different functions.


Phil Mendelsohn

Lottery:    a tax on people who are bad at math

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