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Re: Metastable expressions in Mathematica

  • To: mathgroup at smc.vnet.net
  • Subject: [mg119689] Re: Metastable expressions in Mathematica
  • From: Richard Fateman <fateman at cs.berkeley.edu>
  • Date: Fri, 17 Jun 2011 00:10:51 -0400 (EDT)
  • References: <201106141014.GAA06248@smc.vnet.net> <ita4j9$mb1$1@smc.vnet.net>
On 6/15/2011 4:21 AM, Leonid Shifrin wrote:
> Hi David,
>
> This is a known effect. There is a special command Update, used in such
> cases to force Mathematica to propagate changes like the one you discuss.
>

It is, in some views, an error, to define and implement a programming 
language with a semantics that is not deterministic, but depends on (for 
example) on the page in random access memory on which an expression is 
stored, to tell how it will be evaluated.

Or call Update.

I suspect this "feature" is unique to Mathematica among programming 
languages commercially supported.  The fact that this is "known" to some 
people does not make it harmless. The fact that it almost never affects 
people does not make it harmless either.

RJF
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