mpi/miscellaneous/cartesian.cpp bugfix

jacobi/mpi/miscellaneous/cartesian.cpp

@@ -14,7 +14,7 @@ int main(int argc, char **argv)
   MPI_Comm_size(MPI_COMM_WORLD, &ntasks);
   MPI_Comm_rank(MPI_COMM_WORLD, &task);
 
-  if (argc < 1)
+  if (argc <= 1)
     {
       if (!task)
 	{