Apologies for the lengthy code. I tried a simple (and shorter) piece of code (pasted below) and it still gives me the same error for last few rows. Is this a bug or am I doing something totally wrong? Could anyone please provide some help/pointers ?
PS. beta0 was fixed to 0.001 in the previous code. Also if I manually estimated the integral isnt 0. If I scramble the row order, it is again only the last few rows that dont integrate. Thanks data1<-expand.grid(1:5,0:6,10) names(data1)<-c("ID","TIME", "DOSE") data1<-data1[order(data1$DOSE,data1$ID,data1$TIME),] ed<-data1[!duplicated(data1$ID) , c(1,3)] ed$base=1 ed$drop=1 set.seed(5234123) k<-0 for (i in 1:length(ed$ID)) { k<-k+1 ed$base[k]<-100*exp(rnorm(1,0,0.2)) ed$drop[k]<-0.20*exp(rnorm(1,0,0.5)) } comb1<-merge(data1[, c("ID","TIME")], ed) comb1$disprog<-comb1$base*exp(-comb1$drop*comb1$TIME) comb1$integral=0 hz.func1<-function(t,bshz,beta1, change) { ifelse(t==0,bshz, bshz*exp(beta1*change)) } q<-0 for (m in i:length(comb1$ID)) { q<-q+1 comb1$integral[q]<-integrate(hz.func1, lower=0, upper=comb1$TIME[q], bshz=0.001,beta1=0.035, change=comb1$disprog[q])$value } comb1 [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.