On 2/16/12, Stavros Macrakis <macrakis at alum.mit.edu> wrote: > Actually, a little reflection makes it clear that diff(f(x),g(x)) should > not be an error or a noun form, because in fact it is perfectly > well-defined and meaningful: > > diff(A,B) == ev(diff(A)/diff(B),del) Looks OK to me. OK by me to merge this in. best Robert Dodier