}
rb = (int *)malloc(size*chunk*sizeof(int));
if ( !rb ) {
perror( "can't allocate recv buffer");
free(sb);
MPI_Abort(MPI_COMM_WORLD,EXIT_FAILURE);
}
rb = (int *)malloc(size*chunk*sizeof(int));
if ( !rb ) {
perror( "can't allocate recv buffer");
free(sb);
MPI_Abort(MPI_COMM_WORLD,EXIT_FAILURE);