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MathGroup Archive 2010

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the Operate[] function

  • To: mathgroup at smc.vnet.net
  • Subject: [mg109972] the Operate[] function
  • From: AK <aaarbk at googlemail.com>
  • Date: Thu, 27 May 2010 06:43:09 -0400 (EDT)

Dear all,

Can anyone tell me what the Operate function is good for?
Looking at the help, it says Operate[p, f[x,y]] gives p[f][x,y].
Concentrating on just the rhs above for a moment, the only obvious way
to me of attaching a useful meaning to it is that if p is a function
that takes another function f, and additionally has some anonymous
parameters - I mean #1,#2, etc.; sorry if i've got the terminology
wrong - say for example:
p[f_] = f[#1] + #2^2 &
then p[Sin][4,3] has some meaning
Coming back to Operate's definition, the corresponding lhs wrt is
Operate[p, Sin[4,3]]
which looks problematic first of all because Sin[] is being passed two
parameters instead of  one. (Mathematica complains if you run the
above command, but still gives the answer expected from Operate's
definition)
So unless f happens to take the same number of arguments as the #
arguments in p, the usage seems rather awkward in the first place...
or does its intended application lie precisely in cases where both p
and f have the same number of parameters, or where f can take a
variable number of parameters (I haven't looked at Mathematica
functions with variable number of parameters yet, so I'm just
guessing). Or did I miss the point entirely?

Regards,
AK


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