Is it possible to use the where function in numexpr ? I see some code there for it, but not sure how to use it. While I'm asking, it seems numexpr only does pointwise operations ATM, ie there is no .sum ? Simon. -- Simon Burton, B.Sc. Licensed PO Box 8066 ANU Canberra 2601 Australia Ph. 61 02 6249 6940 http://arrowtheory.com