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Re: FindMinimum

  • To: mathgroup at smc.vnet.net
  • Subject: [mg90565] Re: FindMinimum
  • From: "David Park" <djmpark at comcast.net>
  • Date: Sun, 13 Jul 2008 15:48:05 -0400 (EDT)
  • References: <29862167.1215269377863.JavaMail.jakarta@nitrogen.mathforum.org> <g59tvj$ost$1@smc.vnet.net>

You could us the double underline (_ _ instead of _ but without an extra 
space) to indicate one or more arguments. For example:

f[x__?NumberQ] will accept one or more numbers as arguments.

And you could use

g[{x__}] to indicate a List with one or more elements.

You could use Apply (@@) to apply a function without a list to an indefinite 
list of arguments.

f@@{x1, x2, ...} gives f[x1, x2,...]

And if you define a function as f[x__] then internally you can use {x} to 
get the arguments back into a list.

-- 
David Park
djmpark at comcast.net
http://home.comcast.net/~djmpark/


"pratip chakraborty" <pratip.official at gmail.com> wrote in message 
news:g59tvj$ost$1 at smc.vnet.net...
> Hi,
> I am new in Mathematica and have a problem with "FindMinimum". I want to
> minimize a multi variable numerical function it looks like:
>
> MinFun[{a1,a2,...,ak}]
>
> I also have a code for the gradient computation so I want to  use the
> gradient option of FindMinimum and supply my gradient function which looks
> like:
>
> GradFun[{a1,a2,...,ak}]
>
> Now my problem is in the fact that FindMinimum accepts the cost function 
> and
> the supplied gradient if and only if they are of the form:
>
> MinFun[a1,a2,...,ak]
> GradFun[a1,a2,...,ak]
>
> But I can not every time write a cost function like:
>
> MinFun[a1_?NumericQ,a2_?NumericQ,...,ak_?NumericQ]
> GradFun[a1_?NumericQ,a2_?NumericQ,...,ak_?NumericQ]
>
> because my k can vary among the set of positive integers so I defined my
> cost function with modified test for the argument as
>
> MinFun[a_?(VectorQ[#,NumericQ]&)]
> GradFun[a_?(VectorQ[#,NumericQ]&)]
>
> But I dont know how to define a function
> f[a1_?NumericQ,...,a2000_?NumericQ]:=Block[
> {..},
> ...
> ]
> other than writing so many arguments manualy.
> I tried a wraper like
> g[{a_}]:=f[a]
> But an error occurs saying the shapes dont match.
> Hope some one can help me.
>
> Pratip
>
> 



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