How do I calculate values of the beta function?
| Title | Calculating the beta function | |
| Author | Nicholas J. Cox, Durham University, UK |
The beta function can be defined in terms of the gamma function and thus, calculated using the Stata functions exp() and lngamma(). On the latter, see the section "Mathematical functions" of the [D] Functions. Given positive arguments a and b, the beta function
Β(a,b) = Γ(a) Γ(b) / Γ(a + b)
can be calculated from
exp(lngamma(a) + lngamma(b) - lngamma(a + b))
In this expression, each argument may be a number, a variable, or, more generally, itself an expression.
