dolfin team mailing list archive

[Matthew Knepley <knepley@xxxxxxxxxxx>]

Anders Logg <logg@xxxxxxxxx> writes:

       This flag says:

  1) You configured with --with-clanguage=C++ so that the C++ compiler is used to
     compile the libraries.

  2) The PETSc symbols are NOT mangled when using PETSC_USE_EXTERN_CXX so C code
     can call these symbols.

This is not are normal mode. We believe if you want to compile with C++, then you
want mangled symbols.

     Thanks,

        Matt

> I think we added a
>
> PETSC_CFLAGS="$PETSC_CFLAGS -DPETSC_USE_EXTERN_CXX"
>
> just below the definition of PETSC_CFLAGS in configure.ac.  You need
> to add this, then run scripts/preconfigure and then ./configure again.
>
> We get PETSC_CFLAGS by
>
> PETSC_CFLAGS=`make -s -C $PETSC_DIR getincludedirs PETSC_DIR=$PETSC_DIR BOPT=$BOPT`
>
> which I think should be enough. I don't know why the extra
> -DPETSC_USE_EXTERN_CXX helps on some systems or why it's not included
> with getincludedirs.
>
> /Anders
>
> On Tue, Jun 14, 2005 at 01:38:05PM -0500, Andy Ray Terrel wrote:
>> Sorry to bother you again.  But when I tried to run some things with 
>> dolfin I just got a PETSc Error.  So I tried to rebuild but remembered 
>> that when I built the first time I had to add some linker to PETSc 
>> somewhere.  Well I have forgotten what it was we added to get PETSc to 
>> link.  Do you remember?
>> 
>> Andy
>> 
>> Anders Logg wrote:
>> 
>> >You need to do A and B separately, as two different forms in two
>> >different files.
>> >
>> >In the first file, do something like
>> >
>> >   vector = FiniteElement("Vector Lagrange", "triangle", 1)
>> >
>> >   v = BasisFunction(vector)
>> >   u = BasisFunction(vector)
>> >
>> >   a = v.dx(i)*u.dx(i)*dx
>> >
>> >In the second file, do something like
>> >
>> >   vector = FiniteElement("Vector Lagrange", "triangle", 1)
>> >   scalar = FiniteElement("Lagrange", "triangle", 1)
>> >   
>> >   q = BasisFunction(scalar)
>> >   u = BasisFunction(vector)
>> >
>> >   a = q*u[i].dx(i)*dx
>> >
>> >Compile each form and then assemble separately in DOLFIN to get A and B.
>> >You can then either combine A and B to get the full matrix, or you can
>> >do fixed-point iteration, or you can create something called a
>> >"VirtualMatrix" in DOLFIN which implements the matrix-vector product
>> >for the full matrix in terms of A and B.
>> >
>> >Hope this helps. Ask me again when you need more help.
>> >
>> >/Anders
>> >
>> >On Tue, Jun 14, 2005 at 09:48:43AM -0500, Andy Terrel wrote:
>> > 
>> >
>> >>Hey Anders,
>> >>
>> >>I am having some trouble figuring out how to write some stokes equations 
>> >>up for my project.  So I have the forms:
>> >>
>> >>a = v.dx(j) *u.dy(j)
>> >>b= q*r*dx
>> >>
>> >>and I want to construct the matrix C s.t.
>> >>   [ A   B^t  ]
>> >>C=[ B    0     ]
>> >>
>> >>This is so I can call some mixed methods for the solving of the problem 
>> >>to get the benchmarking results.
>> >>
>> >>If you have time can you help me?
>> >>
>> >>Andy
>> >>
>> >>PS This is to solve (grad(u), grad(v)) - (p, div(v)) = 0,
>> >>                           (div(u), w) = 0.
>> >>
>> >>   
>> >>
>> >
>> > 
>> >
>> 
>
> -- 
> Anders Logg
> Research Assistant Professor
> Toyota Technological Institute at Chicago
> http://www.tti-c.org/logg/
>
>
>

-- 
"Failure has a thousand explanations. Success doesn't need one" -- Sir Alec Guiness