Segmentation fault when constructing variational form

Hi,

I seem to be getting a segmentation fault when trying to construct a variational form. Here is the code that reproduces the error:

from dolfin import *
from numpy import *

# interval [a,b]
N = 100
a = -10.0
b = 10.0
grid = IntervalMesh(N, a, b) # 50 cells, 51 vertices

V = FunctionSpace(grid,"Lagrange", 1)

v = TestFunction(V)
u_next = Function(V)
u_curr = Function(V)
u_prev = Function(V)

c = Constant(1.0)

# initial condition
u_curr.interpolate(Expression("(x[0]>=-ep)*(x[0]<=0.0)*(1/ep * x[0] + 1.0) + (x[0]<=ep)*(x[0]>0.0)*(-1/ep * x[0] + 1.0)", ep = 1.0))
u_prev.assign(u_curr)

f = Constant(0)

# choosing a timestep
dt = 1/100.0

######################################################

# writing the neumann BCs
class AbsorbingBoundaryLeft(SubDomain):
    def inside(self,x,on_boundary):
        return x[0] <= a + DOLFIN_EPS and on_boundary  # first domain is x=a

absorbing_boundary_left = AbsorbingBoundaryLeft() # creating an instance of the Absorbing BC
exterior_facet_domains = FacetFunction("uint",grid)
exterior_facet_domains.set_all(0)
absorbing_boundary_left.mark(exterior_facet_domains,1)

dss = Measure("ds")[exterior_facet_domains]

#####################################################

F = inner(v, (u_next - 2*u_curr + u_prev)/Constant(dt*dt))*dx + inner(grad(u_next), grad(v))*dx + inner(v,(u_next-u_curr)/Constant(dt))*dss(0) + inner(v,(u_curr-u_prev)/Constant(dt))*dss(1)     # implicit time-stepping

And here is the backtrace:

Starting program: /usr/bin/python dalembert.py
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff654f2b1 in ?? () from /usr/lib/python2.7/dist-packages/numpy/core/multiarray.so
(gdb) bt
#0  0x00007ffff654f2b1 in ?? () from /usr/lib/python2.7/dist-packages/numpy/core/multiarray.so
#1  0x00007ffff5d9ceac in ?? () from /usr/lib/python2.7/dist-packages/numpy/core/_dotblas.so
#2  0x000000000052c6d5 in PyEval_EvalFrameEx ()
#3  0x000000000055c594 in PyEval_EvalCodeEx ()
#4  0x00000000005b7392 in PyEval_EvalCode ()
#5  0x0000000000469663 in ?? ()
#6  0x00000000004699e3 in PyRun_FileExFlags ()
#7  0x0000000000469f1c in PyRun_SimpleFileExFlags ()
#8  0x000000000046ab81 in Py_Main ()
#9  0x00007ffff7817ec5 in __libc_start_main (main=0x46ac3f <main>, argc=2, argv=0x7fffffffe088, init=<optimised out>, fini=<optimised out>, 
    rtld_fini=<optimised out>, stack_end=0x7fffffffe078) at libc-start.c:287
#10 0x000000000057497e in _start ()

I am running dolfin 1.4.0 on Ubuntu 14.04. Thank you!

Comments (4)