Dear all, I actually encounter an error message in relation with infinite recursion when I try to call the write.table() function for a matrix of 288 columns (288 hgu133a arrays ). The error message is: Error: evaluation nested too deeply: infinite recursion / options(expression=)? I searched the email archives and I found that I could use the command: options(expressions=10000) to solve this problem but it does not change anything. So I would like to know if I have to increase to 20000 or more in the above line ? Has someone already encountered same problem ??? My goal is to add a column which includes the genesymbol before exporting the data with write.table(). I do this with the functions getSYMBOL and cbind() to add the column at the expreSet I previously transformed in a matrix object. If someone know how to do that in another way which would allow me not to encounter the error message above, please tell me.... Any help kindly accepted..... thanks a lot, Florence.