On Jul 27, 2013, at 2:40 PM, Tom Browder wrote: > The exciting find by Nyah got me looking for such things which may be > useful and I found several tidbits (which are probably well known to > you numerical whiz kids): > > http://en.wikipedia.org/wiki/Fast_inverse_square_root > > > http://www.drdobbs.com/cpp/increasing-compiler-speed-by-over-75/240158941#disqus_thread > > http://www.johndcook.com/blog/2010/01/19/dont-invert-that-matrix/
That last link is particularly relevant. You rare ever need to invert a matrix. We only do that in *very* few places that I'm aware of, e.g., pipe.c's prep might be only place and we probably didn't even need to do it there. The determinant is in a similar boat. Part of the reason for Nyah's find was because those two particular routines were not really used much. So they hadn't really gotten much review. Our heavily used routines tend to be heavily optimized already. Still, it's always great to see an improvement to core routines. To address general usefulness, however, I suggest running a profile to find our hot spots. Aim for order of magnitude improvements and memory cache coherency. ;-) Cheers! Sean ------------------------------------------------------------------------------ See everything from the browser to the database with AppDynamics Get end-to-end visibility with application monitoring from AppDynamics Isolate bottlenecks and diagnose root cause in seconds. Start your free trial of AppDynamics Pro today! http://pubads.g.doubleclick.net/gampad/clk?id=48808831&iu=/4140/ostg.clktrk _______________________________________________ BRL-CAD Developer mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/brlcad-devel
