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MathGroup Archive 2006

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Re: matrix operations -- shared data vs copied

  • To: mathgroup at smc.vnet.net
  • Subject: [mg65956] Re: matrix operations -- shared data vs copied
  • From: "Chris Chiasson" <chris.chiasson at gmail.com>
  • Date: Mon, 24 Apr 2006 06:02:16 -0400 (EDT)
  • References: <e2fkpu$bo8$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

B=A copies A, it doesn't link to A changing A after this statement
doesn't change B

otherwise, this would be invalid input:
a = 1
a = a + 1

You seem to be using a model of thinking about Mathematica that doesn't
really mesh with the way it operates.

B=A is really just like a rule B->A that is always active whenever the
evaluator finds an expression with B in it

B:=A, while it might be tempting to think of as a "link" from B to A,
is really a delayed rule B:>A that is always active whenever the
evaluator finds an expression with B in it

The difference between the two, = and :=, comes into play with patterns
and with the state of A when B is encountered.

If you don't want to read the Mathematica Book one billion times, I
suggest paying someone to instruct you on how to use Mathematica - that
way, you'll only have to read the Mathematica book one million times.
Maybe try Mathematica classes??


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