start MPI py

Python/mpipi.py

+#
+# mpipi.py
+# Neil Gershenfeld 2/6/20
+# calculation of pi by an MPI Numba sum
+# pi = 3.14159265358979323846 
+#
+
+import time
+from numba import jit
+from mpi4py import MPI
+
+@jit(nopython=True)
+def calc(istart,iend):
+   sum = 0.0
+   for i in range(istart,iend+1):
+      sum += 0.5/((i-0.75)*(i-0.25))
+   return sum
+
+NPTS = 100000000000
+comm = MPI.COMM_WORLD
+rank = comm.Get_rank()
+nproc = comm.Get_size()
+if (rank == 0):
+   start_time = time.time()
+   istart = int(1 + NPTS*((rank+0)/nproc))
+   iend = int(NPTS*((rank+1)/nproc))
+   pi = calc(istart,iend)
+   comm.reduce(pi,op=MPI.SUM,root=0)
+   end_time = time.time()
+   mflops = NPTS*5.0/(1.0e6*(end_time-start_time))
+   print("NPTS = %d, pi = %f"%(NPTS,pi))
+   print("time = %f, estimated MFlops = %f"%(end_time-start_time,mflops))
+else:
+   istart = int(1 + NPTS*((rank+0)/nproc))
+   iend = int(NPTS*((rank+1)/nproc))
+   pi = calc(istart,iend)
+   comm.reduce(pi,op=MPI.SUM,root=0)