On Fri, 23 Jan 2004 16:54:14 -0500, David Abrahams wrote: [I wrote:]

...

I'll have a look at zip_view, but on first looks it doesn't exactly look simple :-) Replacing lambda expressions with metafunction classes would be my first strategy.

Well, I replaced zip_view with transform and got the following (non-scientific) results: % time g++ -Wall -W -I. -I/home/pgr/src/boost -DWITH_ZIP_VIEW pq.cpp -c real 0m59.201s user 0m56.444s sys 0m0.475s [without zip_view, using transform] % time g++ -Wall -W -I. -I/home/pgr/src/boost pq.cpp -c real 0m14.074s user 0m13.418s sys 0m0.372s Well, that's much better. (Though there is probably still some room for improvement yet - it's still 3 or 4 fold slower than without the MPL.) How difficult would it be to produce a full family of mpl transform functions? Currently, there are the 1 and 2 sequence forms, but I could use a 3 sequence version :-) (The multi-sequence version is what I would have called "zip_with" from my old F.P. days...) Given the progress I've made, I will put together yet another release of my library. This version allows user choice of the base units in their dimensional analysis (so if you want bananas/second you can have it). It still uses fixed-size vectors of powers, though - so if you have a banana-system and you want to multiply a banana-system-based quantity by a "physical system"-based quantity, it won't let you. Personally, that's the way I like it... phil -- change name before "@" to "phil" for email