[ODE] Non-deterministic behavior

Adam D. Moss aspirin at ntlworld.com
Mon Sep 1 02:57:01 2003

Gary R. Van Sickle wrote:
> In fact it might be better to eliminate the #define entirely, since IIRC the
> scrambled ordering is always a win, isn't it?

Unfortunately not.  But I wouldn't expect the user to be
able to identify (or maintain) the situations where the
non-random ordering is a big win -- I expect that it's
just a #define because
1) Everything in stepfast.cpp is experimental (look at
all the #defines!) and likes to be turned on-and-off for testing
2) Determinism.

If it's any help, the quality of the random numbers used doesn't
have to be very good.

There are lots of RNGs out there.  One that I like
is Blumrand <http://www.tip.net.au/~dbell/> for example.
It gives good random numbers and it's fast (but Linux's glibc's
rand() function is ten times faster still :( ).

Adam D. Moss   . ,,^^   adam@gimp.org   http://www.foxbox.org/   co:3
"I am NOT a nut!  I am the keeper of the seven universal truths!"