Re: Re: Run-time error: A timestep of size zero was assigned

From: Juan Carlos Muñoz Cuartas <juancarlos_munozcuartas_at_yahoo.com>
Date: Fri, 16 Nov 2007 22:31:47 -0600 (CST)

Hi,

I had this error time ago, and the cause was an error
in my parameter file. Look at your parameter file and
verify that the softening length of every particle is
not zero, it is needed to compute the integration time
step.

best!

--- Christopher Erick Moody <cmoody_at_caltech.edu>
escribió:

>
> Hi,
>
> I am running a fairly simple simulation of 1500
> particles in an
> NFW profile. I have a similar error: 'A timestep of
> size zero was
> assigned on the integer timeline!' that always
> occurs on the first
> timestep. It was suggested that the particle in
> question (1495) is an
> outlier and may cause problem. But if I remove it,
> the error simply
> moves to another particle (1348). Removing that
> particle means that
> particle 1493, and then particle 1492 have errors.
> None of these
> particles are outliers, and are relatively close to
> other particles,
> so I'm not sure why GADGET-2 would have problems
> with them to begin
> with.
>
> Any help is appreciated,
> chris
>
> (the error is copied below:)
>
> Begin Step 0, Time: 0, Systemstep: 0
> domain decomposition...
> NTopleaves= 162
> work-load balance=1 memory-balance=1
> domain decomposition done.
> begin Peano-Hilbert order...
> Peano-Hilbert done.
> Start force computation...
> Starting non-periodic PM calculation (grid=0).
> done PM.
> Tree construction.
> Tree construction done.
> Begin tree force.
> tree is done.
> Begin tree force.
> tree is done.
> force computation done.
>
> Error: A timestep of size zero was assigned on the
> integer timeline!
> We better stop.
> Task=0 Part-ID=1495 dt=nan tibase=1.86265e-09
> ti_step=-2147483648
> ac=nan xyz=(-2507.5|-1560.8|-253.42)
> tree=(nan|nannan)
>
> pm_force=(0.000301103|0.000178601|3.49493e-05)
> task 0: endrun called with an error level of 818
> pm_force=(0.000443893|0.000335812|0.000159569)
> task 0: endrun called with an error level of 818
>
>
>
>
> From: Hugo Vicente Capelato <hugo_at_das.inpe.br>
> Date: Tue, 13 Jun 2006 09:52:02 -0300
>
> Hi,
>
> I´m sorry, I did´nt had time yet to regard what is
> happening in detail
> with my simulations and give you a more elaborated
> answer. I´m terribly
> busy these times. Anyway, from past simulations for
> which I encountered
> the same error messages, I think I´m having some
> particles escaping to very
> large distances, as suggested by Ives, and that is
> the cause of my troubles.
>
> To fix this, I think you must remove these particles
> by hand and then reestart
> the simulation ...
>
> Cheers, H.
>
> Quoting Yago Ascasibar <yago_at_aip.de>:
>
> >
> >
> > Hi,
> >
> > I've also had such a problem, and I never really
> understood why. Actually,
> > it
> > seems likely that I do have some isolated
> particles near the boundaries.
> > Could you please elaborate a little bit more on
> what may be happening?
> >
> > Thanks a lot,
> > Yago
> >
> > On Saturday 10 June 2006 12:18, Yves Revaz wrote:
> > > 2) Check that the snapshot from which you
> re-start the simulation do not
> > > contains Nan or Inf numbers, or isolated
> particles at very large
> > > distance from the
> > > center of mass or very large velocities.
> >
> >
> >
> >
> >
>
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>
> --
> HUGO VICENTE CAPELATO
> Divisao de Astrofisica
> Instituto Nacional de Pesquisas Espaciais
> Av. dos Astronautas, 1758
> 12.227-010 Sao Jose dos Campos
> Phone numbers:
> at INPE : 55 12 3945-7207 /-7200 /-6804
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> e-mail: hugo-at-das.inpe.br,hugo-at-astro.iag.usp.br
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===============================================
Juan Carlos Muñoz Cuartas
Grupo de Fisica y Astrofisica Computacional
Estudiante de Maestria
Instituto de Fisica, Universidad de Antioquia
Medellin-Colombia
http://urania.udea.edu.co/jcuartas
===============================================


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Received on 2007-11-17 05:31:59

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