Re: question for compiling a function

*To*: mathgroup at smc.vnet.net*Subject*: [mg113184] Re: question for compiling a function*From*: Ray Koopman <koopman at sfu.ca>*Date*: Sun, 17 Oct 2010 06:05:52 -0400 (EDT)*References*: <i95tjc$65h$1@smc.vnet.net> <i9a55i$nfq$1@smc.vnet.net>

On Oct 15, 11:05 am, Ramiro <ramiro.barran... at gmail.com> > I got feedback from two people and it worked great: > > My new function based on the suggestions is the following: > > example2 = > Compile[{{n, _Real, 1}, {a, _Real}, {b, _Real}, {t, _Real, 1}}, > Gamma[Total[n] + a]/(Times @@ (Gamma[n + 1])* Gamma[a])*b^a* > Times @@ (t^n)/(Total[t] + b)^(Total[n] + a)] > > However, over certain inputs I get the following: > > example2[{97.6203, 8.4788, 21.4204, 46.1755}, 1, 1, > {39.9342, 7.5820, 5.8656, 10.0553}] > > During evaluation of In[277]:= CompiledFunction::cfse: Compiled > expression 1.33128164105707197950410345`12.920368310128088*^315 > should be a machine-size real number. >> > > During evaluation of In[277]:= CompiledFunction::cfex: Could not > complete external evaluation at instruction 4; proceeding with > uncompiled evaluation. >> > > What can I do? > > Thank you, > Ramiro Changing Gamma[x] to (x-1)!, and moving b^a from the first line to the second, we have (Tr@n+a-1)!/(Times@@(n!)*(a-1)!) * b^a * Times@@(t^n) / (Tr@t+b)^(Tr@n+a) The first line = Multinomial@@Append[n,a-1]. The second line = Times@@((Append[t,b]/(Tr@t+b))^Append[n,a]). With[{n = {97.6203, 8.4788, 21.4204, 46.1755}, a = 1, b = 1, t = {39.9342, 7.5820, 5.8656, 10.0553} }, Multinomial@@Append[n,a-1] * Times@@((Append[t,b]/(Tr@t+b))^Append[n,a]) ] 1.06265*^-11