Seems to work, if I unlist the argument at first ;-) Atte > Hi, > > What's wrong here?: > > > v=c(`-`,`+`,1,`^`,`^`,NA,NA,"X",9,"X",2) > > i2=16 > > v[i2] > [[1]] > NULL > > > is.null(v[i2]) > [1] FALSE > > Is it a bug or have I misunderstood something? > > Atte Tenkanen > University of Turku, Finland >