Greetings, This is a beginner question about the MPL. I'm building a general purpose simulation program which will have an optimization module as well as an internal ODE solver which requires derivatives of the implemented algorithm in various forms. Around 1998-2002 there was a lot of enthusiasm for generating the derivatives automatically using expression templates. I'm not quite through with an exhaustive review of the literature but it appears the various efforts ran to ground on the compilation memory and cpu requirements that evaluating expression templates in their original form required. So 1st question, has anybody done something like this with mpl/fusion sequences and algorithms? Has there been an improvement in compile time performance? Do you have any pointers to trivial examples? I've read Alexandrescu, and Abrahams & Gurtovoy and it's not clear to me how to map the expression templates as described in the earlier efforts onto mpl sequences and algorithms. That's probably enough for now. Thanks for any help. Russell