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Re: modulo solving lacking domain?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg126895] Re: modulo solving lacking domain?
  • From: Andrzej Kozlowski <akozlowski at gmail.com>
  • Date: Fri, 15 Jun 2012 15:30:33 -0400 (EDT)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
  • References: <201206120659.CAA25892@smc.vnet.net> <C49675CE-DFFB-4759-A1FC-F853D06D2456@mimuw.edu.pl> <4FD7DD77.6040101@eecs.berkeley.edu> <88093364-D782-410D-8920-E66714C94086@gmail.com> <4FD8A1D4.2030201@eecs.berkeley.edu> <1D1918EF-72C2-4292-8573-C8D8FCD77B15@gmail.com> <4FD8EBC9.9020903@eecs.berkeley.edu> <jrcb1t$dqj$1@smc.vnet.net> <201206150741.DAA24422@smc.vnet.net>

On 15 Jun 2012, at 09:41, Richard Fateman wrote:

> On 6/14/2012 2:31 AM, Andrzej Kozlowski wrote:
>> Why should Wolfram care more about the first kind of users than the second?
>
>
> My primary criterion is that computer algebra systems have as few
> surprises as possible to people who know applied mathematics,
> numerical analysis, and computational science.
>
> When Mathematica surprises me,
> occasionally I mention it here to see how other people
> react.

Perhaps that's how you really see it, but to most other people I think it appears rather different. Take this particular thread. The example you posted was:

Solve[12*n==8,n,Modulus->20]

Now, I would say that most people with a background in mathematics, even if they know nothing about Mathematica would assume that one is asking here for solutions in the ring of integers modulo 20. The other interpretation (the answer is a subset of the integers) is , of course, possible, but unlikely, especially in view of the fact that

Solve[12*n == 8 + 20*k, n, Integers]

{{n -> ConditionalExpression[5*C[1] + 4,
         Element[C[1], Integers] && k == 3*C[1] + 2]}}

already gives that answer. After all, what would be the point of Mathematica having two different ways of solving the integer problem and no way of solving the integers modulo 20 problem?

But having for some reason chosen the integer interpretation and encountered behaviour that did not fit in with it, you declared that you had discovered another "bug", as you do in almost every post. The fact that almost nobody else agrees with you  does not dent your confidence. Clearly everything is a bug to you unless it works the way you would like or expect it to work. You also feign concern for the imaginary confused users whose cause you claim to champion but their gratitude is conspicuous  by its absence.

AK



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