Re: Do firsttimestep, numsteps and run have maximum values?

From: Brian Radak (
Date: Wed Sep 19 2018 - 09:32:29 CDT

I'm 90% sure these are all 32 bit integers in the code. It's also possible
that there is not much overflow checking until a logical error is

What do you specifically have to gain from running so many steps at once? I
can't imagine such a procedure is robust on most hardware.

Firsttimestep is also just a bookkeeping device and doesn't impact output
beyond simple mod operations for flagging output.

On Tue, Sep 18, 2018, 9:44 PM yjcoshc <> wrote:

> Hello everyone,
> I am trying to restart a NAMD simulation which has run for 2133000000
> steps. If I set:
> firsttimestep 2133000000
> run 1000000000
> and then NAMD would run 0 step and exit. I have looked at the NAMD
> source code and found the type of N and firsttimestep is int, not long
> long or int64_t. Does that mean the maximum firsttimestep and total
> steps is the maximum int type integer (2147483647 in gcc)?
> Thanks,
> Haochuan Chen

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