AMBER Archive (2004)

Subject: Re: AMBER: recovering total force array

From: Dave S Walker (dswalker_at_darkwing.uoregon.edu)
Date: Tue Oct 19 2004 - 18:59:00 CDT

> > In runmd.f, I had been trying to replace the velocity array with the force
> > array when making the call to CORPAC(). The forces (and perhaps the
> > velocities and coordinates) in runmd.f I suspect are distributed among the
> > nodes and I had been trying to use a reduce statement to recover all the
> > forces before they're written over in Step 3. Doing this has failed to
> > reproduce the array I get with 1 cpu.
>
> Did you try just forcing the code to go through the "if( init==3 )" block of
> code in subroutine fdist()? That should put all of the forces onto all nodes,
> including the master node, where they can be printed out.
>
> ....dac

Just did and it worked like a charm! Thanks for the simple solution. I
noticed that the if(init==3) statement was nested in an if(mpi_orig)
statement and I was just curious as to what mpi_orig means? I can see
that the outcome of that condition won't matter for this application but
one of my earlier *failed* attempts when working with fdist() was to catch
the forces on the *assumption* that mpi_orig was true.... Thanks again for
your help.

dsw
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