Dear all, I am writing you for two problems I can not solve with R. I used both the 2.6.1 version and the 2.7.0 version. I run a sintax written by a collegue of mine, where there are involved both sparse matrix and quantile estimations. My data begins with 10008*14 observations and at maximum they reach 10008*834 observations. My questions are the following: first, when I give the command X=as.matrix.csr(X) and in matrix X there are some elements that repeat in some rows (i.e in row 1 there is value 3, in row 2 there is again value 3 in the same position), he gives me the following error: Error in if (nnz == 0) { : valore mancante dove ? richiesto TRUE/FALSE (That means : missing value when it is required true/false). When I take off that column with same value that repeats it works well and creates the sparse matrix. Can you help me to correct this problem? Is there a bug in the sparse matrix command? My second problem is the following: after solving this problem I then run a sintax where you run quantile regression repeatedly changing the taus (the quantile estimated). Hence, when I run this program it stops completely sending a microsoft message saying "An error has occurred, the application will be closed" and there is no way to continue to run the program. I thought the problem was the dimension of data, but people told me they are not so huge. Can you help to understand this problem? I tried also on other PC's and gives me the same problem. If the problem is the memory, is there any way to increase it? many thanks alessia