template<typename T>
double ComputePearson(vector<T>&user1,vector<T>&user2)
{
double user1average = 0.0,user2average = 0.0;
double sumuser12 = 0.0,temp1 = 0.0, temp2 = 0.0;
for_each(user1.begin(),user1.end(),[&](T num) //sum the average
{
user1average += num;
});
user1average = user1average/user1.size();
for_each(user2.begin(),user2.end(),[&](T num) // sum the average
{
user2average += num;
});
user2average = user2average/user2.size();
size_t size = user1.size() >= user2.size() ? user2.size():user1.size();
for (int i = 0 ; i < size; ++i)
{
sumuser12 += ((user1[i] - user1average)*(user2[i] - user2average));
}
for_each (user1.begin(),user1.begin()+size,[&](T num)
{
temp1 += pow(num-user1average,2);
});
for_each (user2.begin(),user2.begin()+size,[&](T num)
{
temp2 += pow(num-user2average,2);
});
return sumuser12 / sqrt(temp1*temp2);
}