计算pi的值（第二种方法）

xuyuanchao

代码1：
/* Seriel Code */
#include
#include
#include
static long num_steps = 10000000;
double step;
int main()
{       int i;   
double x, pi, sum = 0.0;
        struct timeval start, finish;
     double diffsec,diffusec;        
gettimeofday(&start,NULL);
step = 1.0/(double) num_steps;
   for (i=0;i

代码2：

#include
#include
#include
#include
static long num_steps = 10000000;
double step;
#define NUM_THREADS 4
int  main()
{   int i;   
   double x, pi, sum[NUM_THREADS];
        struct timeval start, finish;
     double diffsec,diffusec;        
gettimeofday(&start,NULL);
   step = 1.0/(double) num_steps;
   omp_set_num_threads(NUM_THREADS);
  #pragma omp parallel
  {   
  double x;     
  int id = omp_get_thread_num();
    for (i=id, sum[id]=0.0;i
#include
#include
#include
#include
static long num_steps = 10000000;
double step;
#define NUM_THREADS 4
int main()
{   
int i;   
double x, sum, pi=0.0;
        struct timeval start, finish;
     double diffsec,diffusec;        
gettimeofday(&start,NULL);
step = 1.0/(double) num_steps;
omp_set_num_threads(NUM_THREADS);
#pragma omp parallel private(x, sum)
{
  int  id = omp_get_thread_num();
    for (i=id,sum=0.0;i


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