#include<stdio.h>

#include<string.h>

#include<mpi.h>

const int MAX_STRING=;

int main()

{

    char greet[MAX_STRING];

    int comm_sz; //进程数

    int my_rank; //进程号

    MPI_Init(NULL,NULL); //初始化

    MPI_Comm_size(MPI_COMM_WORLD,&comm_sz); //返回进程数

    MPI_Comm_rank(MPI_COMM_WORLD,&my_rank); //返回进程号

    if(my_rank!=)

    {

        sprintf(greet,"Greeting from process %d of %d",my_rank,comm_sz);

        MPI_Send(greet,strlen(greet)+,MPI_CHAR,,,MPI_COMM_WORLD); //通信，发送

    }

    else

    {

        printf("Greeting from process %d of %d",my_rank,comm_sz);

        int q;

        for( q=;q<comm_sz;q++)

        {

            MPI_Recv(greet,MAX_STRING,MPI_CHAR,q,,MPI_COMM_WORLD,MPI_STATUS_IGNORE);//通信，接收

            printf("%s\n",greet);

        }

    }

    MPI_Finalize(); //告知系统MPI已使用完毕

    return ;

}

#include<stdio.h>

#include<string.h>

#include<mpi.h>

double f(double x)

{

    return x*x+x*x*x+;

}

double Trap(double left_endpt,double right_endpt,int trap_count,double base_len)

{

    double estimate,x;

    int i;

    estimate=(f(left_endpt)+f(right_endpt))/2.0; //梯形面积

    for(i =;i<=trap_count-;++i)

    {

        x=left_endpt+i*base_len;

        estimate+=f(x);

    }

    estimate=estimate*base_len;

    return estimate;

}

int main()

{

    int my_rank,comm_sz,n=,local_n;

    double a=0.0,b=3.0,h,local_a,local_b;

    double local_int,total_int;

    int source;

    MPI_Init(NULL,NULL); //初始化

    MPI_Comm_size(MPI_COMM_WORLD,&comm_sz); //返回进程数

    MPI_Comm_rank(MPI_COMM_WORLD,&my_rank); //返回进程号

    h=(b-a)/n;

    local_n=n/comm_sz;

    local_a=a+my_rank*local_n*h;

    local_b=local_a+local_n*h;

    local_int=Trap(local_a,local_b,local_n,h);

    if(my_rank!=)

    {

        MPI_Send(&local_int,,MPI_DOUBLE,,,MPI_COMM_WORLD);

    }

    else

    {

        total_int=local_int;

        for(source=;source<comm_sz;source++)

        {

            MPI_Recv(&local_int,,MPI_DOUBLE,source,,MPI_COMM_WORLD,MPI_STATUS_IGNORE); //接受其他节点信息

            total_int+=local_int;

        }

    }

    if(my_rank==)

    {

        printf("With n=%d trapezoids,our estimated\n",n);

        printf("of the intergral from %f to %f=%.15e\n",a,b,total_int);

    }

    MPI_Finalize();

    return ;

}