doflin.MPI returns NotImplementedError

Question

I have recently upgraded to dolfin 1.6 and now I get an error when using MPI. The simplest code is:

import dolfin

print dolfin.MPI.min(1)

and the error I get is:

    /opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/dolfin/cpp/common.py in min(*args)
    883 
    884         """
--> 885         return _common.MPI_min(*args)
    886 
    887     min = staticmethod(min)

NotImplementedError: Wrong number or type of arguments for overloaded function 'MPI_min'.
  Possible C/C++ prototypes are:
    dolfin::MPI::min< double >(MPI_Comm,double const &)
    dolfin::MPI::min< int >(MPI_Comm,int const &)
    dolfin::MPI::min< unsigned int >(MPI_Comm,unsigned int const &)
    dolfin::MPI::min< std::size_t >(MPI_Comm,std::size_t const &)
    dolfin::MPI::min< dolfin::Table >(MPI_Comm,dolfin::Table const &)

Does anyone know what can be the source of this error?

Thank you

Answer 1

you need to supply an MPI_Comm as the first argument, e.g.

print dolfin.MPI.min(dolfin.mpi_comm_world(), 1)

Usually you can use mesh.mpi_comm() when you have a mesh handy.

Comments

Thank you Chris!

This solves my problem. Was this changed from previous versions? My code was running fine before upgrading.