GCC      = gcc
  MPI      = mpicc
  CFLAGS   = -O3 -fopenmp
  OMP_FLAG = -fopenmp
  RM       =  rm -rf
  
  
  EXE = pi_ser pi_omp pi_task pi_mpi
  
  all : $(EXE) 
  
  #.PHONY: all  clean purge
  
  
  pi_ser: pi_ser.o
  	$(GCC) $(CFLAGS) -o $@ $^
  
  pi_task: pi_task.o
  	$(GCC) $(CFLAGS) -o $@ $^
  
  pi_omp: pi_omp.o
  	$(GCC) $(CFLAGS) $(OMP_FLAG)  -o $@ $^
  
  pi_mpi: pi_mpi.o
  	$(MPI) $(CFLAGS) -o $@  $^
  
  %.o :%.c
  	$(GCC) $(CFLAGS) -c -o $@ $<
  
  
  clean:
  	$(RM) *.o
  
  purge: clean
  	$(RM) $(EXE)