Hi, I guess you need to change the parentheses from: ts=sum(t(m.sham),pick.a[count]) #to
ts=sum(t(m.sham,pick.a[count])) #similarly for tc: for(count in 1:length(pick.a)){ ts=sum(t(m.sham,pick.a[count])) tc=sum(t(m.control,pick.a[count])) output[count,2] <- (ts-tc)/ts } A.K. On Sunday, January 5, 2014 3:47 PM, Mathew Nagendran <mathew.nagend...@mail.utoronto.ca> wrote: I'm relatively new to R. I'm trying to for loop but I keep getting an error message. Can anyone hint at what I am doing wrong please? > m.control=c(1.45,9.40,9.96,4.2,1.86,0.2) > m.sham=c(3.39,23.94,23.62,10.08,2.99,1.09) > > t=function(m, a){(1-exp(-a*m))} #t function defined > > d=function(ts, tc){(ts-tc)/ts} #d function defined > > pick.a=seq(0.01,2,by=0.01) #set of a values defined > > output=cbind(pick.a,d=rep(NA,length(pick.a))) #define array containing a > values in column 1 and d values (outputs) in column 2 > > for(count in 1:length(pick.a)){ + ts=sum(t(m.sham),pick.a[count]) + tc=sum(t(m.control),pick.a[count]) + output[count,2]=(ts-tc)/ts + } Error in -a : 'a' is missing > [[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. ______________________________________________ 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.