Hi, How to fit data to cumulative normal distribution? I tried such way: library(MASS) ed<-c(1:10) cnd<-function(mn,sdd){pnorm(c(1:10),mn,sdd)} fitdistr(ed,cnd,start=list(mn=mean(ed),sdd=sd(ed))) ..but an error occured: Error in solve.default(res$hessian) : function Lapack 'dgesv': system are exactly singular Thank you for help Antony --