dolfin team mailing list archive

["Dag Lindbo" <dag@xxxxxxxx>]

It will take me some time to write a stand-alone code that someone else
can run, so hang on.

Gdb says:

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread -1208269120 (LWP 12715)]
0x004776ed in dolfin::DiscreteFunction::updateVectorDimension ()
   from /usr/local/lib/libdolfin.so.0


Valgrind says the same (I guess):

==12683== Invalid read of size 4
==12683==    at 0x1BA106EA:
dolfin::DiscreteFunction::updateVectorDimension() (in
/usr/local/lib/libdolfin.so.0.0.0)
==12683==    by 0x1BA10966:
dolfin::DiscreteFunction::DiscreteFunction(dolfin::uBlasVector&,
dolfin::Mesh&, dolfin::FiniteElement&) (in
/usr/local/lib/libdolfin.so.0.0.0)
==12683==    by 0x1BA13B30:
dolfin::Function::Function(dolfin::uBlasVector&, dolfin::Mesh&,
dolfin::FiniteElement&) (in /usr/local/lib/libdolfin.so.0.0.0)
==12683==    by 0x804E1FB:
dolfin::Vec_Func_fcns::L2_Error_DF_DF(dolfin::Mesh&, dolfin::Function&,
dolfin::Function&) (Vec_Func_fcns.cpp:41)
==12683==    by 0x808F6E6: main (LSM_test.cpp:135)
==12683==  Address 0x1BD79D68 is 0 bytes inside a block of size 12 free'd
==12683==    at 0x1B9098CF: operator delete(void*) (vg_replace_malloc.c:155)
==12683==    by 0x804F87D:
dolfin::Scalar_L2Error::LinearForm::FunctionElement_1::~FunctionElement_1()
(Scalar_L2Error.h:228)
==12683==    by 0x1BA0D703: dolfin::Form::~Form() (in
/usr/local/lib/libdolfin.so.0.0.0)
==12683==    by 0x1BA0FBCA: dolfin::LinearForm::~LinearForm() (in
/usr/local/lib/libdolfin.so.0.0.0)
==12683==    by 0x80539FF:
dolfin::Scalar_L2Error::LinearForm::~LinearForm() (Scalar_L2Error.h:23)
==12683==    by 0x804E52B:
dolfin::Vec_Func_fcns::L2_Error_Exact(dolfin::Mesh&, dolfin::Function&,
dolfin::Function&) (Vec_Func_fcns.cpp:29)
==12683==    by 0x808F666: main (LSM_test.cpp:131)
pure virtual method called
terminate called without an active exception



> On Sun, Oct 01, 2006 at 06:35:51PM +0200, Dag Lindbo wrote:
>> Hi all,
>>
>> I'm a bit confused about passing a Function to a function and using it
>> to
>> assemble some system. What I'm doing is passing a Function, "func", by
>> reference, to a function, foo, where func goes into a form and that form
>> is assembled etc.
>>
>> Vector& Another_Class::foo(Mesh& mesh, Function& func)
>> 	{
>> 		AAA::BilineraForm a
>> 		AAA::LinearForm L(func)
>>
>> 		FEM:assemble(...)
>> 		lu_solver.solve(...)
>>
>> 		return x;
>> 	}
>>
>> This works fine, but when the context that called foo (e.g. main)
>> resumes
>> something has happended to "func". The next time it is referenced the
>> porgram terminates with a segmentation violation. To get around this I
>> can
>> copy the data to local Vector in foo:
>>
>> Vector& Another_Class::foo(Mesh& mesh, Function& func)
>> 	{
>> 		Vector vec = func.vector();
>> 		Function func2(vec,mesh,func.element());
>>
>> 		AAA::BilineraForm a
>> 		AAA::LinearForm L(func2)
>>
>> 		FEM:assemble(...)
>> 		lu_solver.solve(...)
>>
>> 		return x;
>> 	}
>>
>> I would dearly like to avoid this extra copy of a large vector. How
>> should
>> one do this?
>>
>> Regards,
>> Dag Lindbo
>
> This should not happen so it looks like a bug. Passing a function as
> argument to a form only has the effect that the pointer to the
> function is placed in a list. During assembly, all functions in the
> list will be interpolated to each element. The pointer is never
> deleted.
>
> See if you can produce a simplest possible example that breaks and
> maybe we can find out what goes wrong. Also check with valgrind if you
> have it availabe and see if you can locate the offending line.
>
> /Anders
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