only split if cmake flag is set

CMakeLists.txt

@@ -3,6 +3,7 @@ project(MLMC)
 
 set(SPACE_DIM 2 CACHE STRING "SPACE_DIM")
 set(USE_FFTW ON CACHE STRING "USE_FFTW")
+set(USE_SPLITTED_COMMS ON CACHE STRING "USE_SPLITTED_COMMS")
 set(USE_SPACETIME OFF CACHE STRING "USE_SPACETIME")
 #set(COMPILER_OPTIMIZE -O0 CACHE STRING "COMPILER_OPTIMIZE")
 set(COMPILER_OPTIMIZE -O3 CACHE STRING "COMPILER_OPTIMIZE")