dolfin team mailing list archive

["Evan Lezar" <evanlezar@xxxxxxxxx>]

On Thu, Aug 21, 2008 at 5:49 PM, Ola Skavhaug <skavhaug@xxxxxxxxx> wrote:

> Evan Lezar skrev den 21/08-2008 følgende:
> > Thanks for the speedy replies from all of you.
> >
> > Firstly platform information
> >
> > I am running ubuntu hardy, gcc version 4.2.3, swig 1.3.33, python 2.5
> with
> > release versions of numpy and scipy.  I am building dolfin directly from
> > source with mpi, but have not enabled petsc or any of the other optional
> > packages.
> >
> > What other information do you require?
> >
> > In terms of my specific problem, see the following code snippet:
> >
> > from dolfin import *
> > import numpy as N
> >
> > mesh = UnitSquare(4,4)
> > element = FiniteElement("Nedelec", "triangle", 0)
> >
> > ### Code to assemble system matrices and solve an eigenvalue problem
> >
> > # h_e is an array of coefficients associated with the degrees of freedom
> in
> > the system obtained from the eigenvectors V
> > h_e = V[:,sorted_index[first_index]]
> >
> > # setup a function to evaluate - the solution of the magnetic field
> > field = Function(element, self.mesh, h_e)
> >
> > # arbitrary point to evaluate the field
> > points = N.array((0.5,0.25))
> > # array to store the field value at a point
> > H = N.array((0.0,0.0))
> >
> > print "pre_eval"
> >
> > #evaluate the function
> > field.eval(H, points)
> >
> > # Ouput the field at the point
> > print "H",
> > print H
> >
> >
> > When I run this code, I get the following output:
> >
> > pre_eval
> > [labby:25160] *** Process received signal ***
> > [labby:25160] Signal: Segmentation fault (11)
> > [labby:25160] Signal code: Address not mapped (1)
> > [labby:25160] Failing at address: 0xde8f58ec
> > [labby:25160] [ 0] [0xb7f81440]
> > [labby:25160] [ 1] /usr/bin/python(PyEval_EvalCodeEx+0x6e7) [0x80cb0d7]
> > [labby:25160] [ 2] /usr/bin/python(PyEval_EvalFrameEx+0x565e) [0x80c92de]
> > [labby:25160] [ 3] /usr/bin/python(PyEval_EvalCodeEx+0x6e7) [0x80cb0d7]
> > [labby:25160] [ 4] /usr/bin/python(PyEval_EvalFrameEx+0x565e) [0x80c92de]
> > [labby:25160] [ 5] /usr/bin/python(PyEval_EvalCodeEx+0x6e7) [0x80cb0d7]
> > [labby:25160] [ 6] /usr/bin/python(PyEval_EvalCode+0x57) [0x80cb227]
> > [labby:25160] [ 7] /usr/bin/python(PyRun_FileExFlags+0xf8) [0x80ea6d8]
> > [labby:25160] [ 8] /usr/bin/python(PyRun_SimpleFileExFlags+0x199)
> > [0x80ea979]
> > [labby:25160] [ 9] /usr/bin/python(Py_Main+0xa35) [0x8059335]
> > [labby:25160] [10] /usr/bin/python(main+0x22) [0x80587f2]
> > [labby:25160] [11] /lib/tls/i686/cmov/libc.so.6(__libc_start_main+0xe0)
> > [0xb7de8450]
> > [labby:25160] [12] /usr/bin/python [0x8058761]
> > [labby:25160] *** End of error message ***
> >
> > With a previous build I have gotten different output and was able to
> > actually display the contents of H, but it would shill crash once the
> method
> > where the code was being run was terminated.  I logged a bug against it
> at
> > http://www.fenics.org/cgi-bin/bugzilla/show_bug.cgi?id=55
> >
> > As I said in my mail, I see myself using fenics in the long run and would
> > like to get involved as much as possible, but some pointers as to where
> to
> > start would be much apprciated.
>
> Have you implemented the C++ version as well, such that you know that what
> you
> do is correct?
>

> Clearly, we are not catching what's going wrong here (missing check of some
> sort).
>
> My guess is that the error occurs in site-packages/dolfin/function.py, when
> the Function is initialized. Can you boil down the example to a shorter
> script
> and post it to this list? I'll have a look at it.
>
> Ola
>

Hi

I have not implemented a C++ version, but I will look into it - I am a
little more comfortable with python at the moment, but I suppose I need to
jump into the deep end :)

I will write a simple example script and then attach that.

Evan