[Gmsh] Removing a volume from an ambient volume

[Travis Thompson]

Hello.  I have been working with Gmsh for a finite elements project at
Texas A&M university in college station, tx.

I am new to Gmsh and have been stuck on a particular problem for a
while now; I was hoping maybe someone could shed some light on it.
The setup is fairly simple.  I have a 3 dimensional rectangle which
completely contains another 3 dimensional object.

The object inside the box is completely closed; i will refer to this
object as Object A.  If I attach a volume element to object A and mesh
the box + object A everything works wonderfully.  I get a nice 2d mesh
on the bounding box and a nice 3d mesh inside object A.

The problem is that I need a 3d mesh inside the bounding box and i
want *no mesh* in the interior of object A (that is, I want to mesh
the complement of Object A with respect to the bounding box).

What I have tried:
a) I have tried attaching a volume element to the ambient bounding box
and selecting Object A as 'a hole'
b) I have tried attaching a volume element to the bounding box and a
volume element to Object A with the intention of Deleting the volume
element attached to object A *after* computing the mesh.

However both (a) and (b) lead to gmsh crashing (same error on both
windows and Linux versions)
The error is:

----------------------------
Assertion Failed!

Program: c:\program files\gmsh-2.2.4-Windows\gmsh.exe
File: tetgen.cxx
Line: 22506

Expression: matchflag == true
---------------------------

I would imagine that what I am trying to do is quite basic; ie:
meshing the complement of an object inside an ambient object.  I have
been through the documentation but due to my lack of familiarity with
Gmsh I have failed to figure out a method.

If anyone can shed any light on this I would greatly appreciate it!

Thank you in advance!

-Travis Thompson
Graduate Student
Dept of Mathematics, Texas A&M University