openMP-数据并行化小例子

/*
功能：循环并行化
作者：刘荣
时间：2012.11.15
*/
#include<iostream>
#include<omp.h>
#include<Windows.h>
#include<time.h>
#include<cmath>
//变量声明
const int numVector = 10000;
double a[numVector] ,b[numVector] ,c[numVector];

int main()
{

srand( (unsigned)time(NULL));
//初始化数据

for(int i = 0;i < numVector; i++)
{
a[i] = i * rand()*1.0/RAND_MAX;
b[i] = i * rand()*1.0/RAND_MAX;
}
//相关数据声明
double start, end, diffTime1, diffTime2;
//串行程序
start = clock();//开始计时

for(int i = 0;i < numVector; i++)
{
c[i] = a[i]*b[i]+sqrt(a[i]/b[i]);
}

end = clock();//结束计时
diffTime1 = end - start;
printf("串行所用的时间：%0.3f s \n",diffTime1/1000);

//并行化程序
start = clock();//开始计时

#pragma omp parallel for
for(int i = 0;i < numVector; i++)
{
c[i] = a[i]*b[i]+sqrt(a[i]/b[i]);
}

end = clock();//结束计时
diffTime2 = end - start;
printf("并行所用的时间：%0.3f s \n",diffTime2/1000);
printf("加速比：%0.3f \n",diffTime1/diffTime2);
return 0;
}