Fixed the communicator construction when the teams have different sizes

src/hierarchical.cpp

 #include <iostream>
 #include <mpi.h>
 #include <ginac/ginac.h>
+#include <math.h> // ceil
 
 #include "products.h"
 #include "utils_parall.h"
@@ -23,7 +24,7 @@ void create_communicators_hierarch( MPI_Comm& COMM_FOREMEN, MPI_Comm& COMM_TEAM
        color_foreman is set to 1 if I am the root or a foreman */
 
     int color_foreman, workers_per_foreman;
-    workers_per_foreman = ( np - 1) / NBFOREMEN;
+    workers_per_foreman = ceil( (double)( np - 1) / (double)NBFOREMEN );
     if( ROOT == rank ) {
         color_foreman = 1;
     } else {
@@ -42,10 +43,8 @@ void create_communicators_hierarch( MPI_Comm& COMM_FOREMEN, MPI_Comm& COMM_TEAM
     if( ROOT == rank ) {
         color_team = 0;
     } else {
-        workers_per_foreman = ( np - 1) / NBFOREMEN;
-        color_team = 1 + ( (rank-1) / workers_per_foreman );
+        color_team = 1 + floor( ( (rank-1) / workers_per_foreman ) );
     }
-    
     MPI_Comm_split( MPI_COMM_WORLD, color_team, rank, &COMM_TEAM );
 
 #if  DEBUG
@@ -99,7 +98,7 @@ gi::ex multiply_1level_foreman_hierarch_distribute_work( tensor3D_t& T, matrix_i
     }
     
     /* Distribute the work */
-    /* Very copy/paste from multiply_1level_master -> possible refactoing here */
+    /* Very copy/paste from multiply_1level_master -> possible refactoring here */
     
     while( input.size() > 0 ) {
         MPI_Recv( &len, 1, MPI_UNSIGNED, MPI_ANY_SOURCE, MPI_ANY_TAG, comm_team, &status );