#include<stdio.h>

#include<stdlib.h>

#include<malloc.h>

#include<math.h>

#include"mpi.h"

#define PI 3.1415

int main(int argc,char** argv)

{

        int rank,p,i;     //

    double* sbuf;     //

    double rbuf[];

    double add;       //

        double  h;            //

    int a;            //

    double sum ;      //

    double* ssum;

    double asum    ;

    int n=;

        //初始化

        MPI_Init(&argc,&argv);

        //从命令行获取开启的线程数

        MPI_Comm_size(MPI_COMM_WORLD,&p);

        //获取本线程的线程号

        MPI_Comm_rank(MPI_COMM_WORLD,&rank);

    add= (*PI)/p;

        if(rank==)

        {

        ssum=(double*)malloc(sizeof(double)*p);

            sbuf=(double*)malloc(sizeof(double)*p);

       printf("Process's begin x is ");

      for(i=;i<p;i++)

      {

      //计算各块起始x

       sbuf[i]=add*(i);

      printf(" %lf ",sbuf[i]);

         }

          printf("\n");

         }

        //向各个线程分发起始x值

        MPI_Scatter(sbuf,,MPI_DOUBLE,rbuf,,MPI_DOUBLE,,MPI_COMM_WORLD);

    h=(add)/n;

    for(i=;i<n;i++)

    {

    double x=rbuf[]+h*i+h/;

    sum=sum+cos(x)*h;

     }

    printf("Process %d 's sum is %.2lf\n",rank,sum);

    //收集各线程计算结果

    MPI_Gather(&sum,,MPI_DOUBLE,ssum,,MPI_DOUBLE,,MPI_COMM_WORLD);

    if(rank==)

    {

      for(i=;i<p;i++)

      {

       asum=asum+ssum[i];

       }

      printf("cos x 0~2PI de ji fen shi %.2lf\n",asum);

      }

    MPI_Finalize();

    return ;

}