title: How to parralize vector operations
body: <p>I want to add two vectors parrallel and use mpi4py to do that. 
  But I am not very familliar with mip4py so my question is if this code below is already parallaized? When i use the expression <code>mpirun -n 3 python3 Übung2.py</code>does 3 stands for the number of workers?</p>
  
  <p>here is my code:</p>
  
  <pre><code>na=10**6
  va = np.random.rand(na,1)
  vaa = np.random.rand(na,1)
  
  from mpi4py import MPI
  import time
  
  comm = MPI.COMM_WORLD
  rank = comm.Get_rank()
  size = comm.Get_size()
  # master process
  sume=0
  VA=[]
  if rank == 0:
      start_time = time.time()
  
  
      # master process sends data to worker processes by
      # going through the ranks of all worker processes
      for i in range(1, size):
          VA.append(va+vaa)
          comm.send(VA, dest=i, tag=i)
          print(VA)
          #print('Process {} sent data:'.format(rank), data)
          sume = sume + (time.time() - start_time)
  
  
  # worker processes
  else:
      # each worker process receives data from master process
      data = comm.recv(source=0, tag=rank)
      #print('Process {} received data:'.format(rank), data)
  
  print(sume)
  
  </code></pre>
  
  <p>Thank you </p>