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MathGroup Archive 2007

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Re: Evaluation Question

  • To: mathgroup at smc.vnet.net
  • Subject: [mg76523] Re: Evaluation Question
  • From: Szabolcs <szhorvat at gmail.com>
  • Date: Wed, 23 May 2007 05:33:29 -0400 (EDT)
  • Organization: University of Bergen
  • References: <f2u57d$k2n$1@smc.vnet.net>

hoffmannick wrote:
> Can anyone help me solve the following problem?
> 
> I have a function of 3 variables, let's say
> f[a_, b_, c_] = a + b + c
> 
> Now I need to evaluate the function at some given points.  To evaluate
> at a single point I would do
> f[0,0,1]
> 
> For the point (0,0,1)
> 
> Now here is the main question.
> I need to evaluate this function at the points (0,0,0) through (1,1,1)
> That would be the points:
> 0,0,0
> 0,0,1
> 0,1,0
> 0,1,1
> 1,0,0
> 1,0,1
> 1,1,0
> 1,1,1
> 
> I'm testing these for approx 32 different functions.  Is there an easy
> way that I can define the function and then have it test all the
> points for me?  It will always be those finite points listed above.
> 
> I looked into the mathematica documentation and it said how to do this
> with a function of a single variable, but it didn't say how to do it a
> function of more than one variable.
> 
> I really appreciate your help

Use Apply[] at level 1 of the list of argument-triples (look up the 
third argument of Apply in the docs).

Apply[f, IntegerDigits[Range[2^3]-1, 2, 3], 1]

or

f @@@ IntegerDigits[Range[2^3]-1, 2, 3]

If you have many functions, f, g, h etc., use

(# @@@ IntegerDigits[Range[2^3] - 1, 2, 3]) & /@ {f, g, h}

Or if you found out how to do it for a function of a single variable (I 
think you mean Map[]), you could define f to be such a function:

f[{a_, b_, c_}] := a + b + c

Now you can use /@ (Map) instead of @@@ (Apply)

(# /@ IntegerDigits[Range[2^3] - 1, 2, 3]) & /@ {f, g, h}

Szabolcs



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