As Philip Viton noted in the General forum, D. gives strange results. This is true even for rank 0 functions.
f=:% (f d. (i.6)) 1 1 _1 2 _6 24 _120 (f D. (i.6)) 1 1 _1 1.9984 111022 _3.33067e12 7.77156e19 This is not a new problem: the same occurs with J504. I assume there is some instability in the numerical differentiation algorithm. Best wishes, John ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
