并行计算上机代码

多线程求PI：

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>

double res;

typedef struct Args {
    long n;
    long begin;
    long step;
} Args;

void *cal(void *arg);

int main(int argc, char *argv[]) {
    long i;
    long n = atol(argv[1]);
    int np = atoi(argv[2]);
    Args *arg;
    double* val;

    pthread_t *pid;
    pid = (pthread_t *)malloc(np * sizeof(pthread_t));
    
    res = 0.0;
    for (i = 0; i < np; i++) {
        arg = (Args *)malloc(sizeof(Args));
        arg->n = n;
        arg->begin = 2*i+1;
        arg->step = np;
        pthread_create(&pid[i], NULL, cal, (void *)arg);
    }
    for (i = 0; i < np; i++) {
        pthread_join(pid[i], (void *)val);
    }
    res = res * 4.0;
    printf("%lf
", res);
    free(pid);
    return 0;
}

void *cal(void *_arg) {
    long i;
    double val;
    Args *arg = (Args *)_arg;
    
    val = 0.0;
    for (i = arg->begin; i <= arg->n; i += 2*arg->step) {
        if(i % 4 == 3) val -= 1.0 / i;
        else val += 1.0 / i;
    }
    res += val;
    return NULL;
}

多线程矩阵乘法：

　　矩阵乘法用多线程实现

　　幂次用快速幂实现

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>

#define maxn 3
#define Matrix double

typedef struct Args {
    long n;
    long begin;
    long step;
} Args;

Matrix res[maxn][maxn] = {{1.0, 0.0, 0.0},{0.0, 1.0, 0.0},{0.0, 0.0, 1.0}};         /*结果矩阵*/
Matrix A[maxn][maxn] = {{0.1, 0.2, 0.3}, {0.4, 0.5, 0.4}, {0.3, 0.2, 0.1}};      /*原矩阵*/
Matrix tmp[maxn][maxn];                /*中间量*/
long i, j, k;

void *cal(void *arg);
void *cal1(void *_arg);
void output(Matrix a);

int main(int argc, char *argv[]) {
    long n = atol(argv[1]);
    int np = atoi(argv[2]);
    Args *arg;

     for(i = 0; i < maxn; i++){
        for(j = 0; j < maxn; j++){
            printf("%.20lf ", A[i][j]);
        }
        puts("");
    }
    puts("");
    pthread_t *pid;
    pid = (pthread_t *)malloc(np * sizeof(pthread_t));

    while(n > 0){
        if(n & 1){
            /* res = res * A*/
            pthread_t *pid;
            pid = (pthread_t *)malloc(np * sizeof(pthread_t));
            for(i = 0; i < maxn; i++){
                for(j = 0; j < maxn; j++){
                    tmp[i][j] = 0.0;
                }
            }
            for (i = 0; i < np; i++) {
                arg = (Args *)malloc(sizeof(Args));
                arg->n = n;
                arg->begin = i+1;
                arg->step = np;
                pthread_create(&pid[i], NULL, cal, (void *)arg);
            }
            for (i = 0; i < np; i++) {
                pthread_join(pid[i], NULL);
            }
            free(pid);
//            printf("tmp ********************
");
//            for(i = 0; i < maxn; i++){
//                for(j = 0; j < maxn; j++){
//                    printf("%.20lf ", tmp[i][j]);
//                }puts("");
//            }
            for(i = 0; i < maxn; i++){
                for(j = 0; j < maxn; j++){
                    res[i][j] = tmp[i][j];
                }
            }
        }
        /* A = A * A*/
        pthread_t *pid;
        pid = (pthread_t *)malloc(np * sizeof(pthread_t));
        for(i = 0; i < maxn; i++){
            for(j = 0; j < maxn; j++){
                tmp[i][j] = 0.0;
            }
        }
        for (i = 0; i < np; i++) {
            arg = (Args *)malloc(sizeof(Args));
            arg->n = n;
            arg->begin = i+1;
            arg->step = np;
            pthread_create(&pid[i], NULL, cal1, (void *)arg);
        }
        for (i = 0; i < np; i++) {
            pthread_join(pid[i], NULL);
        }
        free(pid);
        for(i = 0; i < maxn; i++){
            for(j = 0; j < maxn; j++){
                A[i][j] = tmp[i][j];
            }
        }
        n >>= 1;
    }

/*
    for (i = 0; i < np; i++) {
        arg = (Args *)malloc(sizeof(Args));
        arg->n = n;
        arg->begin = i+1;
        arg->step = np;
        pthread_create(&pid[i], NULL, cal, (void *)arg);
    }
    for (i = 0; i < np; i++) {
        pthread_join(pid[i], NULL);
    }
*/
    for(i = 0; i < maxn; i++){
        for(j = 0; j < maxn; j++){
            printf("%.20lf ", res[i][j]);
        }
        puts("");
    }
    puts("");
    return 0;
}

void *cal(void *_arg) {
    long i;
    Args *arg = (Args *)_arg;

    for(i = arg->begin; i <= maxn*maxn; i += arg->step){
        int row = i / maxn;
        if(i % maxn == 0){
            row--;
        }
        int column = ((i % maxn) + maxn - 1) % maxn;
        for(k = 0; k < maxn; k++){
            tmp[row][column] += res[row][k] * A[k][column];
        }
    }
    return NULL;
}

void *cal1(void *_arg) {
    long i;
    Args *arg = (Args *)_arg;

    for(i = arg->begin; i <= maxn*maxn; i += arg->step){
        int row = i / maxn;
        if(i % maxn == 0){
            row--;
        }
        int column = ((i % maxn) + maxn - 1) % maxn;
        for(k = 0; k < maxn; k++){
            tmp[row][column] += A[row][k] * A[k][column];
        }
    }
    return NULL;
}

 

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1、标准c中的结构体内部是不可以定义函数的，c++可以

2、实验平台下不允许变量的重复定义