我正在尝试使用simpsons规则进行数值积分,所以我认为最好的方法是在三个线程中,一个用于2'一个用于3' s然后是结束边界。
但我是新手,我还在学习一些东西。 但是,我真的不知道这有什么问题,我创建了具有其属性的线程并将其发送出去,然后我释放属性并尝试加入线程,因为它们变得可用,我做错了吗? 有没有更好的方法呢?
感谢您的帮助!
代码附件::
#include <stdio.h>
#include <math.h>
#include <pthread.h>
#include <unistd.h>
#include <time.h>
#include <signal.h>
#include <stdlib.h>
#include <sys/wait.h>
#define PI 3.1415926535897932384626433832795028841971693993751058
float h_val, x_i, a_bound, b_bound, n_slices;
long double temp_vals[4];
int first, second = 0;
void * threes (void *t)
{
long double a_n;
long double seq_threes;
long double x_i;
long tid = (long)t;
long double threes_sum = 0;
for(int i = 1; i < n_slices; i++)
{
a_n = .25*((6*i)-(pow((-1),i))-3);
x_i = a_n * (PI / n_slices);
printf("Value of i :: %d Value of x_i :: %Lf \n", i, x_i);
seq_threes = 3*pow(((sin(PI*sin(x_i)))/(PI*sin(x_i))),2);
threes_sum = threes_sum + seq_threes;
}
temp_vals[0] = threes_sum;
pthread_exit((void*) t);
return EXIT_SUCCESS;
}
void * twos (void *t)
{
long double a_n;
long double seq_twos;
long double x_i;
long double twos_sum = 0;
long tid = (long)t;
for(int i = 1; i < n_slices; i++)
{
a_n = 3*i;
x_i = a_n * (PI / n_slices);
printf("Value of i :: %d Value of x_i :: %Lf \n", i, x_i);
seq_twos = 2*pow(((sin(PI*sin(x_i)))/(PI*sin(x_i))),2);
twos_sum = twos_sum + seq_twos;
}
temp_vals[1] = twos_sum;
pthread_exit((void*) t);
return EXIT_SUCCESS;
}
void* ends(void *t)
{
long double a_n, a_0;
long double x_n = n_slices;
long double x_0 = 0;
long tid = (long)t;
pid_t end_to_end;
printf("End to ends:: x_n ==%Lf \n",x_n);
end_to_end = fork();
if (end_to_end == 0)
{
x_0 = 0 * (PI / n_slices);
a_0 = 1;
printf("a_0 :: %Lf :: x_0 :: %Lf\n",a_0, x_0);
exit(1);
}
else
{
x_n = n_slices * (PI / n_slices);
a_n = pow(((sin(PI*sin(x_n)))/(PI*sin(x_n))),2);
printf("a_n :: %Lf || x_n :: %Lf\n",a_n, x_n);
wait(NULL);
}
temp_vals[2] = a_0 + a_n;
pthread_exit((void*) t);
return EXIT_SUCCESS;
}
int main(int argc, char *argv[])
{
pid_t id;
pthread_t ends_thread, twos_and_threes[3];
pthread_mutex_t thread_locker;
void * status;
long t;
n_slices =(atof(argv[1])) ;
n_slices = ((n_slices + 3 - 1) / 3) * 3 ;
printf("Running with slice size :: %lf (must be multiple of 3)\n", n_slices);
pthread_attr_t attr;
pthread_attr_init(&attr);
pthread_mutex_init(&thread_locker, NULL);
pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
//Child Process
if(pthread_create(&twos_and_threes[0], &attr,ends,(void*) t))
return EXIT_FAILURE;
if(pthread_create(&twos_and_threes[1],&attr,twos,(void*)t))
return EXIT_FAILURE;
if(pthread_create(&twos_and_threes[2],&attr,threes,(void*)t))
return EXIT_FAILURE;
wait(NULL);
pthread_attr_destroy(&attr);
for(int i = 0 ; i < 3 ; i++)
pthread_join(twos_and_threes[i], &status);
/*
twos();
threes();
ends();
*/
temp_vals[3] = temp_vals[0]+temp_vals[1] +temp_vals[2];
printf( "Temp vals :: %Lf :: %Lf :: %Lf :: %Lf\n",\
temp_vals[0],temp_vals[1],temp_vals[2],temp_vals[3]);
wait(NULL);
long double result =((3*(PI/ n_slices))/8)*(temp_vals[3]) ;
printf("Result == %Lf \n",result);
pthread_exit(NULL);
return EXIT_SUCCESS;
}
谢谢,解决了这个错误,以及其他一些更改,代码已经更新以反映。
答案 0 :(得分:0)
您正在一个进程中创建线程,然后在另一个进程中销毁它们。当你fork()
时,只有调用fork()
的线程将出现在子节点中,并且在子节点中创建的线程不会神奇地出现在父节点中。
你不需要fork()
这里以及线程。只需等待主线程中的线程完成。