contact of polyhedron

Since my problem is likely to be associated with the size of polyhedrons. Here is one of my polyhedrons:
4 vertices:
-0.01841946 -0.01834445 -0.01710164
-0.01667621 -0.016184 -0.007231501
-0.01121877 -0.01043363 -0.009731257
-0.01786081 -0.01001629 -0.01491588

My other polyhedrons are also 4 vertices and have the similar size of the polyhedron above.

Please read [1] if you wish to solicit help :-)

[1]https://www.yade-dem.org/wiki/Howtoask

Hi Robert:
I know my description may be unclear but I tried to provide more information.
I read the codes about polyhedron and found that my codes blocked in function Polyhedron Simplify(Polyhedron P,Real limit) in Polyhedra_support.cpp.
I want to know
1.what is this function used for?

I also checked the errored interaction and its relative polyhedrons, and found that the 2 polyhedrons,
Poly1 init dofs:
Vector3(-4.229972e-11,0.05,-0.01572352)
Vector3(-0.008409783,0.03956479,-0.025)
Vector3(-0.006184036,0.03689339,-0.01840207)
Vector3(-0.01039558,0.04890738,-0.01572352)

Poly2 init dofs:
Vector3(-8.637007e-10,0.04044868,-0.025)
Vector3(-4.229972e-11,0.05,-0.01572352)
Vector3(0.00397562,0.04082184,-0.01813537)
Vector3(0.005226423,0.04972609,-0.025)

the 2 polys have a common point and in my simulation, they will have a very very small intersection at this point after several steps.

I want to know
2. If the intersection is very very small, will it got wrong? and why?

In fact, if I adjust the time step to a larger one, it does run smoothly. I guess that's because the intersection is larger?

3.Will reducing SIMPLIFY_LIMIT work?
Yours,
Joe

Thank you so much for helping create a sustainable resource for future users.

Let's start with item 2) from [1].

"If you encounter an error, share it." In other words, copy and paste the error here.

Next, let's look at item 3) from [1]. Without an MWE, we cannot reproduce the "error" that you are referring to and therefore we are throwing darts at a pool table ;-)

If you prefer that we don't investigate your particular error, instead but you simply want to talk about the code, then at the very least we need to make sure we are looking at the same trunk, the same file, the same line. Can you link to the line number for this function "Simplify(Polyhedron P,Real limit)"?

[1]https://www.yade-dem.org/wiki/Howtoask

Also please provide information about operating system, yade version, method installation (package/source) and CGAL version and how it was installed.
Thanks
Jan

Hi Robert Jan:
Here are my codes:

from libyade import yade
from yade import *
from yade import utils,polyhedra_utils
from minieigen import Vector3, Matrix3, Matrix6

# basic materials
matS = PolyhedraMat(young=1.e14,poisson=0.1,frictionAngle=0.2,density=1e7)
O.materials.append(matS)

POLY1=[
Vector3(-1.1252229043696602e-9,0.04044867969995926,-0.02500000014298641),
Vector3(-2.404624131217237e-10,0.0499995,-0.015723519897073306),
Vector3(0.003975620285304186,0.04082183933765579,-0.018135369824275445),
Vector3(0.005226423189199525,0.04972559,-0.02500000012427156)]

POLY2=[
Vector3(1.222315982854378e-10,0.0499995,-0.015723520027142578),
Vector3(-0.008409782917328579,0.03956479014801928,-0.02500000011219652),
Vector3(-0.006184036292741935,0.03689338966056221,-0.018402069868769105),
Vector3(-0.010395579966696341,0.0489073797989524,-0.015723519982404767)]

poly1 = utils.polyhedron(material=matS, vertices=POLY1,fixed=True)
poly2 = utils.polyhedron(material=matS, vertices=POLY2,fixed=True)
O.bodies.append(poly1)
O.bodies.append(poly2)

# basic YADE engines
O.engines=[
   ForceResetter(),
   InsertionSortCollider([Bo1_Facet_Aabb(),Bo1_Polyhedra_Aabb(),Bo1_Wall_Aabb()],verletDist=0.01),
   InteractionLoop(
      [Ig2_Wall_Polyhedra_PolyhedraGeom(), Ig2_Polyhedra_Polyhedra_PolyhedraGeom(), Ig2_Facet_Polyhedra_PolyhedraGeom()],
      [Ip2_PolyhedraMat_PolyhedraMat_PolyhedraPhys()], # collision "physics"
      [Law2_PolyhedraGeom_PolyhedraPhys_Volumetric()] # contact law -- apply forces
   ),

   NewtonIntegrator(damping=0.1,gravity=(0,0,0.0)),
]

O.dt = 0.00001

O.step()

POLY1 and POLY2 contain the coordinates of the 2 polys when it got error. It got error in line 271-289 in function Simplify in /pkg/dem/Polyhedra_support.cpp

I use yade-2017.01a on Ubuntu16.04, but I can't get my CGAL version. CGAL is installed in 2015, so I think its version>4.5. I didn't enable lbmflow linsolv pfvflow sph which don't have any influence on polyhedron mudule.

Thanks for your patience!
Yours,
Joe

I run your code and I do not get an error. Is there a certain number of iterations required to reproduce the error? What is the error we are looking for....?

Hi Robert:
I still got segmentation fault (core dumped) even if I changed a device...
I decide to check the error myself but I want to know what is the function Simplify( line 271-289 /pkg/dem/Polyhedra_support.cpp) used for and how it works?
Yours,
Joe

I **think** (cannot find any reference but I am concerned I read it somewhere) that with newer CGAL, this kind of errors was solved..
Could you try the same code on a newer system (could be just virtual machine)?
Jan

Hi Jan:
It works!
Thanks for your reply!
Yours,
Joe