Greetings: I have a simple issue; the (probably cumbersome) code follows: #_______________________________________________ datmod=(dat) datmod$em96gbr=ifelse(datmod$em96gbr > 0, log(datmod$em96gbr), datmod$em96gbr) datmod$em96spbr=ifelse(datmod$em96spbr > 0, log(datmod$em96spbr), datmod$em96spbr) datmod[,4:8]=log(datmod[,4:8]) datmod[,10:13]=log(datmod[,10:13]) datmod[,15:28]=log(datmod[,15:28]) datmod[,4:23]=datmod[,4:23]-datmod$p97 datmod[,25:26]=datmod[,25:26]-datmod$p97 #__________________________________________________ It works fine with the exception of datmod[,26] where the operation "- datmod$p97" is not performed. I thought this might be interesting enough to share with the list :-) mihai [[alternative HTML version deleted]]