linux下pthread梯形积分法代码

以下是一个使用 pthread 实现梯形积分法的示例代码：

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

#define NUM_THREADS 4
#define N 1000000

double a = 0.0, b = 1.0;
double h = (b - a) / N;
double integral = 0.0;

void* trapezoidalRule(void* rank) {
    long my_rank = (long) rank;
    double local_a = a + my_rank * (N / NUM_THREADS) * h;
    double local_b = local_a + (N / NUM_THREADS) * h;
    double local_integral = 0.0;

    for (int i = 1; i <= N / NUM_THREADS; i++) {
        double x0 = local_a + (i - 1) * h;
        double x1 = local_a + i * h;
        local_integral += (x1 - x0) * (sin(x0) + sin(x1)) / 2.0;
    }

    integral += local_integral;
    return NULL;
}

int main(int argc, char* argv[]) {
    pthread_t threads[NUM_THREADS];
    long thread;
    for (thread = 0; thread < NUM_THREADS; thread++) {
        pthread_create(&threads[thread], NULL, trapezoidalRule, (void*) thread);
    }

    for (thread = 0; thread < NUM_THREADS; thread++) {
        pthread_join(threads[thread], NULL);
    }

    printf("With n = %d trapezoids, our estimate\n", N);
    printf("of the integral from %f to %f = %.15e\n", a, b, integral);
    return 0;
}

这个程序将使用 4 个线程并行计算梯形积分，其中 `trapezoidalRule` 函数是每个线程执行的函数。在主函数中，我们创建了 4 个线程，并等待它们完成，并输出最终的积分结果。