Estimate(s) from the conditional lognormal distribution based on given parameters
Arguments
rnd
Vector of quantiles
meanlog
The meanlog parameter
sdlog
The sdlog parameter
lower_bound
The lower bound to be used (current time)
s_obs
is the survival observed up to lower_bound time,
normally defined from time 0 as 1 - plnorm(q = lower_bound, meanlog, sdlog) but may be different if parametrization has changed previously