lnBeta

Computes the natural logarithm of the beta function for parameters a and b.

The beta function is defined as gamma(a) * gamma(b) / gamma(a + b). The logarithmic form avoids overflow for large parameters. It is used internally by the regularized incomplete beta function and by beta distributions.

Example:

lnBeta(2.0, 3.0) // -2.4849... (ln(1/12))
lnBeta(0.5, 0.5) // 1.1447... (ln(pi))

Return

the natural logarithm of beta(a, b).

Parameters

a

the first shape parameter. Must be positive.

b

the second shape parameter. Must be positive.