From: Jérôme Hénin (
Date: Fri Dec 08 2017 - 12:41:33 CST

Hi everyone,

If you use Tcl scripts to do moderate amounts of number-crunching, you've
certainly noted that repeated calls to expr take a long time.

To improve this, I've written a kind of vector extension to expr, that
allows running a series of computations on vector data in one go. It's
implemented in C, so it's quite fast.

Please give it a try and tell me if it helps (or if it doesn't, what's

And since we're here chatting, a reminder : for lightning-fast PBC wrapping
(and unwrapping) in orthorhombic cells, there is qwrap: