Handle vector-coefficients as ICs and BCs

[Øyvind Evju]

Would be more intuitive in the problem-interface if initial and boundary conditions could be provided as vectors instead of list of scalars.

[Øyvind Evju]

Is this possible in dolfin 1.3? Useful?

[Martin Sandve Alnæs]

Not without a performance penalty. We currently do this (pseudocode):

DirichletBC(scalar_space, scalar_function, ...)
DirichletBC(vector_space.sub(i), scalar_function, ...)

which works out fine, but I don't think this works:

DirichletBC(scalar_space, vector_function.sub(0), ...)

and definitely not this:

DirichletBC(scalar_space, vector_expression.sub(0), ...)

I suggest we add issues to dolfin for the features we need and see what we can do for 1.4.