Compute pressure/energy on timestep 0

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1

It seems that the total pressure and energy are always calculated on
timestep 0, even if they are not needed/never called for in the input
script. Is there a way to change this?

Thanks,

Stan

2

It seems that any pre-defined compute (total energy, pressure) and any
user-defined compute in the input script is calculated on timestep 0,
even if it is never used... It would be nice to check and see if a
compute is ever used, and if it is not, don't calculate it on timestep
0.

Thanks,

Stan

3

I think that the "run 0" trick is the only way to obtain thermodynamic
properties before the start of the simulation (and this is a VERY
useful trick). Why would you want to eliminate it? I mean, this
calculation is not expensive because it happens only once AND is very
useful....

Rodrigo

4

I am trying to get accurate timings of a new method with and without
pressure/energy turned on. I'm only using a few timesteps, and even if
I turn off the pressure/energy in the input script, it is still
calculated on timestep 0, which influences the results. I have to
manually set the eflag and vflag variables in the codes and recompile
to get accurate run times. I don't want to eliminate the "run 0"
trick if it is actually needed/called for in the input script, but
right now the total pressure/energy are still calculated on timestep 0
even there is *nothing* related to them in the input script...

5

You can't eliminate it on the very first run.
But you can on subsequent runs, using
the "pre no" option for the run command.

Steve