[hpf@gauss presentation]$ g77 -o pi_mpi.exe pi_mpi.f -I$MPI_INCL -L$MPI_LIB -lmpich_ch_p4 -fno-second-underscore

[hpf@gauss presentation]$ mpirun_ch_p4 -np 4 pi_mpi.exe

 MPI initialized with  4 processors
 Enter the number of intervals (0 to quit)
 100000000
 Approximation for pi is   3.14159265
 The error is   4.00568467E-13
 Elapsed time is  2.91000009
 Enter the number of intervals (0 to quit)
 0

[hpf@gauss presentation]$