How do I calculate values of the beta function?
| Title |
|
Calculating the beta function |
| Author |
Nicholas J. Cox,
Durham University, UK |
| Date |
November 2001 |
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 help on
math functions. Given 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.
|
