文章內(nèi)容

MPI 并行解方程

發(fā)布時(shí)間: 2012/8/9 17:21:34

基本算法逐步縮小函數(shù)值異號(hào)的范圍最后逼近最終解

所有線程計(jì)算中地位相同計(jì)算范圍與self號(hào)相應(yīng)的區(qū)段值把x較小值做為解只支持單個(gè)解

lx做為計(jì)算范圍和終止條件最后由主線程顯示結(jié)果

1.2.#include "mpi.h"
3.
-

•#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();