Re: question for compiling a function

*To*: mathgroup at smc.vnet.net*Subject*: [mg113148] Re: question for compiling a function*From*: Ray Koopman <koopman at sfu.ca>*Date*: Fri, 15 Oct 2010 13:51:48 -0400 (EDT)*References*: <i95tjc$65h$1@smc.vnet.net>

On Oct 13, 8:31 pm, Ramiro <ramiro.barran... 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 xample[n,\[Alpha]] == Multinomial@@n * Pochhammer[1.+Tr@n,\[Alpha]-1.]