The LOGNORMDIST function returns the lognormal distribution. @x is the value for which you want the distribution, @mean is the mean of the distribution, and @stdev is the standard deviation of the distribution.
Performing this function on a string or empty cell simply does nothing. if @stdev = 0 LOGNORMDIST returns #DIV/0! error. if @x<=0, @mean<0 or @stdev<0 LOGNORMDIST returns #NUM! error.