Fixed all-to-all communication in distributed SpMV

      localOnlySpan.first = local_span.getElement( 0 );

      localOnlySpan.second = local_span.getElement( 1 );

      // copy the buffer into all rows of the commPattern* matrices

      // copy the buffer into all rows of the preCommPattern* matrices

      // (in-place copy does not work with some OpenMPI configurations)

      Matrices::Dense< IndexType, Devices::Host, int > preCommPatternStarts, preCommPatternEnds;

      preCommPatternStarts.setLike( commPatternStarts );

      preCommPatternEnds.setLike( commPatternEnds );

      for( int j = 0; j < nproc; j++ )

      for( int i = 0; i < nproc; i++ ) {

         commPatternStarts.setElementFast( j, i, span_starts.getElement( i ) );

         commPatternEnds.setElementFast( j, i, span_ends.getElement( i ) );

         preCommPatternStarts.setElementFast( j, i, span_starts.getElement( i ) );

         preCommPatternEnds.setElementFast( j, i, span_ends.getElement( i ) );

      }

      // assemble the commPattern* matrices

      CommunicatorType::Alltoall( &commPatternStarts(0, 0), nproc,

      CommunicatorType::Alltoall( &preCommPatternStarts(0, 0), nproc,

                                  &commPatternStarts(0, 0), nproc,

                                  group );

      CommunicatorType::Alltoall( &commPatternEnds(0, 0), nproc,

      CommunicatorType::Alltoall( &preCommPatternEnds(0, 0), nproc,

                                  &commPatternEnds(0, 0), nproc,

                                  group );

   }