logPmf
Returns the natural logarithm of the probability mass at k for this beta-binomial distribution.
Computed directly in log-space using the log-binomial-coefficient and the log-beta function: ln C(n, k) + ln B(k + alpha, n - k + beta) - ln B(alpha, beta). This avoids overflow for large trial counts where intermediate products would exceed floating-point range.
Return
the natural log of the probability mass at k. Returns Double.NEGATIVE_INFINITY when the mass is zero.
Parameters
k
the number of successes at which to evaluate the log-probability.