I don't understand how to use cumulative distribution functions in sagemath. For example, I'd like to define a function N(x) as N(x)=1-F(x) where F is a cumulative log-normal distribution However, if I try
W = RealDistribution('lognormal',[1.5,.6])
N(x) = W.cum_distribution_function(x)
it does not seem to work at all
