Functions implementing the Bernoulli-lognormal distribution, in which zero values
occur with probability 1-prob and non-zero values follow a lognormal
distribution with meanlog and sdlog parameters.
dblnorm gives a probability density function (pdf),
pblnorm gives the cumulative distribution
function (cdf), qblnorm gives the quantile function (inverse cdf),
and rblnorm is used for generating random variates.