Dear all, many statistical functions and elements extraction are very different for data in the both forms Several examples sum() denote list lis = ... sum(lis) is essentially the same as sumr({lis}) but sum({lis}) is different In the opposite direction: analogue of sumc({lis}) is aggregate(lis,const,"sum")[3:] mean() In the contrast to sum() it is not allowed for a matrix Again, mean(lis) corresponds to meanc({lis}) Overall mean for a matrix of general shape is meanc(vec(a_matrix)) The behavior of min and max is similar to that of mean Overall median for a matrix is quantile(vec(a_matrix),0.5) In my opinion, it would be much transparent if sum() mean(), etc were overall sums and means    and sumc(), sumr() etc were defined both for lists and matrices    these functions could have additional boolean/integer parameter    indicating how to treat missing values     Oleh