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Re: question for compiling a function

  • To: mathgroup at smc.vnet.net
  • Subject: [mg113137] Re: question for compiling a function
  • From: Leonid Shifrin <lshifr at gmail.com>
  • Date: Fri, 15 Oct 2010 13:49:46 -0400 (EDT)
  • References: <201010140327.XAA06163@smc.vnet.net>

Hi Ramiro,

For your particular example, you don't really need Compile. You can use the
fact that Gamma is Listable:

exampleAlt[n_, \[Alpha]_] :=
 Gamma[Total[n] + \[Alpha]]/Times @@ Gamma[n + 1]


Regards,
Leonid



On Wed, Oct 13, 2010 at 8:27 PM, Ramiro <ramiro.barrantes at gmail.com> wrote:

> Hello,
>
> I am doing some MCMC on mathematica and performance is becoming an
> issue.  So the low hanging fruit would be compiling some functions.
> Below is an portion of the key one:
>
> example[n_, \[Alpha]_] :=
>  Gamma[Plus @@ n + \[Alpha]]/Times @@ (Gamma[# + 1] & /@ n)
>
> "n" is a vector of positive reals.  However, I don't know how big it
> is, it will usually be just 4 o 5 numbers but could be anything from 1
> to 200 size vector.
>
> Any suggestions?
>
> Thanks in advance,
> Ramiro
>
>


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