Hello! Does apply() not work with customized functions? Here is a simple example: AddSeven<-function(n){n+7} AddSeven(3) [1] 10 M<-matrix(nrow=2,ncol=2,data=c(1,2,3,4),byrow=TRUE) M [,1] [,2] [1,] 1 2 [2,] 3 4 apply(x=M,margin=c(1,2),fun=AddSeven) Error in match.fun(FUN) : argument "FUN" is missing, with no default Thanks for your help! -Steve Pfeiffer [[alternative HTML version deleted]]