logPmf
Returns the natural logarithm of the probability mass at k.
The log-mass is useful when working with very small probabilities that would underflow to zero in regular floating-point arithmetic. Every implementation provides a direct formula rather than computing ln(pmf(k)), which avoids unnecessary precision loss.
Return
the natural log of the probability mass at k. Returns Double.NEGATIVE_INFINITY when the mass is zero.
Parameters
k
the integer outcome at which to evaluate the log-mass.