Attempt to find max value on mesh in parallel

2

Dear @CoE2845,
Next time, please encapsulate your code with 3x` to ensure proper formatting.
You simply need to use MPI communicators for the problem at hand:

from dolfin import *
from mpi4py import MPI
mesh = UnitSquareMesh(10,10)
Space = FunctionSpace(mesh, "CG", 1)
T = project(Expression("10*x[0]+100*x[1]", degree=2), Space)
max_T = max(T.vector())

print("T_max is : {0:.2e} on Proc {1:d}".format(max_T, MPI.COMM_WORLD.rank))
MPI.COMM_WORLD.barrier()
max_T = mesh.mpi_comm().allreduce(max_T, op=MPI.MAX)
if MPI.COMM_WORLD.rank ==0:
    with open("test.txt", "w") as f:
        f.write(str(max_T))
    print("Global max is {0:.2e} on Proc {1:d}".format(max_T, MPI.COMM_WORLD.rank))