用pthreads实现梯形积分法
时间: 2023-10-09 17:17:20 浏览: 143
Program using Pthreads
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梯形积分法是一种数值积分方法,可以用于数值求解函数的积分。下面是用pthreads实现梯形积分法的示例代码:
```c
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#define NTHREADS 4
double a = 0.0, b = 1.0;
int n = 10000000;
double h;
double result = 0.0;
pthread_mutex_t mutex;
void* trapezoid_rule(void* rank) {
long my_rank = (long) rank;
int local_n = n / NTHREADS;
double local_a = a + my_rank * local_n * h;
double local_b = local_a + local_n * h;
double local_result = 0.0;
double x_i;
for (int i = 0; i < local_n; i++) {
x_i = local_a + i * h;
local_result += (f(x_i) + f(x_i + h)) * h / 2.0;
}
pthread_mutex_lock(&mutex);
result += local_result;
pthread_mutex_unlock(&mutex);
return NULL;
}
double f(double x) {
return x * x;
}
int main(void) {
pthread_t threads[NTHREADS];
h = (b - a) / n;
pthread_mutex_init(&mutex, NULL);
for (long rank = 0; rank < NTHREADS; rank++) {
pthread_create(&threads[rank], NULL, trapezoid_rule, (void*) rank);
}
for (long rank = 0; rank < NTHREADS; rank++) {
pthread_join(threads[rank], NULL);
}
pthread_mutex_destroy(&mutex);
printf("Result: %lf\n", result);
return 0;
}
```
在这个示例代码中,我们使用了四个线程计算积分。每个线程计算一个局部积分,最后将局部积分相加得到整个积分。为了保证线程安全,我们使用了互斥锁来控制对共享变量`result`的访问。
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