In a computation, I need Log[Beta[alpha+j,beta-j+n]]
of some kind.
Is there a LogBeta
function built-in to avoid any under/over flow problems?
There is one in R, called lbeta(a,b)
.
I could rewrite them in terms of Gamma
functions and thus in terms of LogGamma
. But I am lazy. I search a bit for it, just can't seem to find it.
So Mathematica does not have it?
On a related matter, Beta
sometimes gives bad results, see here.
Beta[a,b]==Gamma[a] Gamma[b]/Gamma[a+b]
SologBeta[a_, b_]:= LogGamma[a] + LogGamma[b] - LogGamma[a+b]
$\endgroup$logbeta[]
is now available when googling the site :) $\endgroup$