Re: [ESPResSo-devel] Segmentation fault

[Axel Arnold]

Hi,

if the second particle id is always a bond number, then most likely you did 
not specify the correct number of bond partners in the Bonded_ia array. If you 
need two bond partners, but specify only one, then of course the next bond of 
the particle will be stored where you expect the other particle's ID. If you 
look at the last bond of a particle, there will be a 0.

Axel

On Wednesday 13 June 2012 20:36:56 Ulf Schiller wrote:
> Hi,
> 
> I implemented something similar a while back and did not find any
> problem in principal. Eventually I did not follow this route because I
> needed a 'real' triangulation structure with neighbor information for
> triangles etc.
> 
> First thing to check in your case is whether the bonds get set correctly
> in the first place. If so, you have to find out when and why that
> information gets overwritten. Most likely the best way to find out is
> using a debugger. I'm afraid I can't say more than that based on the
> information you provided.
> 
> Let us know if we can help any further.
> 
> Cheers,
> Ulf
> 
> On 06/13/2012 07:17 PM, Markus Gusenbauer wrote:
> > Hi all,
> > 
> > We defined new bonding forces for an elastic object (interacting
> > particles in a triangular mesh representing the surface of the object,
> > like constant volume force, constant area force). For this we have to
> > calculate current volume and area of the object. This is done before the
> > actual force calculation in Espresso because we need information about
> > every particle in the object. We made exactly the same loop through the
> > cells and particles as used in calculate_verlet_ia(). The method works
> > fine with 7 objects (every
> > object has around 400 particles forming a triangle mesh). Suddenly with
> > 8 objects we get a segmentation fault. Looks like that a bond is broken
> > (not on the same node). But this error is also when using just 1 node
> > (Is this possible?). After analyzing we found out that this bond (that
> > holds 1 particle with 2 neighbours forming a triangle) has a wrong
> > neighbour id. So exactly the 2nd neighbour of the broken bond points not
> > to a particle id, but to a different bond id. Could it be that we came
> > into an out-of-array error and reading information from somewhere else?
> > We have more than 25000 different bonds because every triangle in the
> > mesh need to be defined and also other forces (like stretching between
> > only 2 particles). On the tcl-level (in the tcl-start-script) the bonds
> > are all correct when printing particle information. We are using version
> > 3.1.0!
> > 
> > We would really appreciate any ideas that could solve our problem!
> > 
> > Thanks,
> > Markus
-- 
JP Dr. Axel Arnold
ICP, Universität Stuttgart
Pfaffenwaldring 27
70569 Stuttgart, Germany
Email: address@hidden
Tel: +49 711 685 67609