我们从Python开源项目中，提取了以下6个代码示例，用于说明如何使用mpi4py.MPI.MAX。
def norm(self,x): """ norm = sum(x*x) """ nbduplicates = (self.np0*self.mp0)/(self.np*self.mp) # computenorm is done in Fortran self.typenorm='l2' t0 = time() # MPI.COMM_WORLD.Barrier() if self.typenorm=='l2': local_sum = computenorm(self.msk,x,self.nh) t1 = time() self.time['norm']+=t1-t0 self.ncalls['norm']+=1 z=MPI.COMM_WORLD.allreduce(local_sum,op=MPI.SUM)/ nbduplicates z=sqrt(z) t0 = time() self.time['reduce']+=t0-t1 self.ncalls['reduce']+=1 if self.typenorm=='inf': local_z= computemax(self.msk,x,self.nh) t1 = time() self.time['norm']+=t1-t0 self.ncalls['norm']+=1 z=MPI.COMM_WORLD.allreduce(local_z,op=MPI.MAX) t0 = time() self.time['reduce']+=t0-t1 self.ncalls['reduce']+=1 return z
def mpi_max(value): global_max = np.zeros(1, dtype='float64') local_max = np.max(value).astype('float64') MPI.COMM_WORLD.Reduce(local_max, global_max, op=MPI.MAX) return global_max[0]
def set_msk_laplacian(self,prevlev=0,mskf=0): """ set the good mask and the laplacian using previous level """ if prevlev==0: self.msk=mskf self.compute_A_atfinest() else: mskf=prevlev.msk*1.0 coef=ones((self.mv,self.nv)) finetocoarse(prevlev,self,mskf,coef) self.msk[coef<=0.5]=0 np=self.np mp=self.mp myrank=self.myrank iloc=myrank%np jloc=(myrank//np)%mp nh=self.nh self.compute_A_atcoarser(prevlev,self.msk) # # coefficient for the Jacobi iteration, A[:,:,4] is the main diagonal # val=abs(self.A[:,:,4]).max() # self.coef = MPI.COMM_WORLD.allreduce(val, op=MPI.MAX) # if self.coef!=0.: # self.coef=1./self.coef # else: # if self.myrank==0: # print('matrix diagonal is zero') # print('fix something!') # exit() # buffer for 'smoothertwice' the Fortran subroutine self.yo=zeros((3,self.nv)) #----------------------------------------
def max(self, x_local): return self._reduce(x_local, MPI.MAX)
def max_at_root(self, x_local): return self._reduce_at_root(x_local, MPI.MAX)
def _sync_i_max(self): sendbuf = numpy.array(self._i_max, dtype='i') recvbuf = numpy.empty(1, dtype='i') log_debug(logger, self._log_prefix + "Entering allreduce with maximum index %i" % (self._i_max)) self.comm.Allreduce([sendbuf, MPI.INT], [recvbuf, MPI.INT], op=MPI.MAX) self._i_max = recvbuf[0] log_debug(logger, self._log_prefix + "After reduce: i_max = %i" % self._i_max)
