[codes-ross-users] RNG behavior change in codes-base master

[Jenkins, Jonathan P.]

Hi all,

FYI, pretty soon I’ll be pushing a change to the codes-base repository that changes the random number generator (RNG) behavior for models using CODES.

In CODES, we have a heavily-used function called codes_local_latency that adds a tiny amount of random noise to event timestamps to help prevent event ties and keep parallel simulations deterministic. Previously, we were using it with the default RNG (i.e. lp->rng[0]. BTW, ROSS allows multiple random number generators for each LP. Cool!!!). However, we'd like to insulate the RNG sequences that “matter” (those called by the user) from those that don't (our noise function), to improve model determinism in the face of minor changes that affect the number of RNG functions called.

No end-user code needs to be updated, but model behavior that depends on RNG will change.

Thanks,
John