Using FiPy to solve a 1D diffusion problem under a potential profile

[WANG Lingjian]

Hello everyone,

I am trying to solve a 1D diffusion problem in a shape like the following 
equation using FiPy.
<a href="http://imgur.com/35xl6Cg";><img src="http://i.imgur.com/35xl6Cg.png"; 
title="source: imgur.com" /></a>
Where U(z) is a 1D potential fitted from experiment data. I created this U_z as 
a CellVariable like the following:
```
U_z = CellVariable(name="potential", mesh=mesh)
U_z.setValue(fitted_function(x) * D * beta)

``` 

>From my understanding, this equation can be interpreted using FiPy syntax as
```
F_z = U_z.faceGrad
eqX = TransientTerm() == (DiffusionTerm(coeff=D) + ConvectionTerm(coeff=F_z))

```
But when I try to solve it using commands that look like this,
```
for step in range(steps):
    eqX.solve(var=phi, dt=timeStepDuration)
    print "time step at {}".format(step)
    viewer.plot()

```
I encounter a Segmentation fault error with no further information indicating 
any possible error.

Could anyone tell me:
#1 Is there any misunderstanding in the above processes(i.e. treating the dU/dz 
term as a ConvectionTerm, using .faceGrad ...)?
#2 Is there any option for debugging the Segmentation fault error? 

Thanks in advance.

In case that software environment issue, I provide some system information and 
FiPy test information below.

[SYSTEM INFO]
System: fedora17(Beefy Miracle)
Python version: anaconda2 4.4.0
FiPy installation method: "conda create --name MYFIPYENV --channel guyer 
--channel conda-forge fipy" .

[FiPy test status]
Testing of FiPy using
```
python -c "import fipy; fipy.test()"
```
Fails with AttributeError: 'module' object has no attribute 'testFiPy'.

But test using 
```
python setup.py test

``` 
under the FiPy source folder gives
###############
FAILED (failures=4)
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Skipped 45 doctest examples because neither `lsmlib` nor `skfmm` can be found 
on the $PATH
Skipped 2 doctest examples because `lsmlib` must be used to run some tests
Skipped 1 doctest examples because `skfmm` must be used to run some tests
###############

_______________________________________________
fipy mailing list
fipy@nist.gov
http://www.ctcms.nist.gov/fipy
  [ NIST internal ONLY: https://email.nist.gov/mailman/listinfo/fipy ]