MPI 并行解方程

基本算法 逐步縮小函數值異號的范圍 最后逼近最終解

所有線程計算中地位相同 計算范圍與self號相應的區段值 把x較小值做為解 只支持單個解

lx做為計算范圍和終止條件 最后 由主線程顯示結果

1.2.#include "mpi.h"  
3.
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•#include <stdio.h>  
•#include <stdlib.h>   • 
•#define END 999999   •#define CON 1   •#define RES 2   •//calculation values   •#define OST 0.000001   •#define IL 0.5   •#define IH 1.5   •#define THD 0.0001   •float func(float x) {  •    //any function   •    return (x*x-1);  •} 
•int main(int argc,char *argv[]) {     •    int self,size;  •    MPI_Init(&argc,&argv); 
•    MPI_Comm_rank(MPI_COMM_WORLD,&self); 
•    MPI_Comm_size(MPI_COMM_WORLD,&size); 
•    MPI_Request r; 
•    MPI_Status s; 
•    float lx=IL,hx=IH;//end point value   •    float res=END;  •    float *data=(float *)malloc(size*sizeof(float));//for gather   •    while(((hx-lx)/size>THD)&&(END!=lx)) {  •        res=END; 
•        float step=(hx-lx)/size;  •        lx=lx+step*(self); 
•        hx=lx+step-OST; 
•        float lv=func(lx);  •        float hv=func(hx);  •        if(lv*hv<0) {  •            //continue calculation   •        } else {  •            if(0==lv) {  •                //end and mark to pass low to root   •                res=lx; 
•            } else if(0==hv) {  •                //end and mark to pass high to root   •                res=hx; 
•            } else {  •                //wait for a new lx hx   •            } 
•            lx=END; 
•        } 
•        //gather all lx   •        MPI_Allgather(&lx,1,MPI_FLOAT,data,1,MPI_FLOAT,MPI_COMM_WORLD); 
•        int prc=END;  •        for(int i=0;i<size;++i) {  •            if(END!=data[i]) {  •                prc=i; 
•                lx=data[i]; 
•            } 
•        } 
•        if(END==prc) {//all ends   •            if(END!=res) {//send res to root   •                MPI_Ssend(&res,1,MPI_FLOAT,0,0,MPI_COMM_WORLD); 
•            } 
•        } else {  •            MPI_Bcast(&hx,1,MPI_FLOAT,prc,MPI_COMM_WORLD); 
•        } 
•    } 
•    if(0==self) {//show result   •        if(END==lx) {  •            MPI_Recv(&lx,1,MPI_FLOAT,MPI_ANY_SOURCE,0,MPI_COMM_WORLD,&s); 
•            for(int i=0;i<size;++i) {  •                if(END!=data[i]) {  •                    lx=data[i]; 
•                } 
•            } 
•        } else {  •            lx=(hx+lx)/2; 
•        } 
•        printf("result %f \n",lx);  •    } 
•    free(data); 
•    MPI_Finalize(); 

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