invsqrt vs fastinvsqrt

hello.cpp

#include "glm.h"
#include<vector>
#include <iostream>
#include<Windows.h>
double PCFreq = 0.0;
__int64 CounterStart = 0;

void StartCounter()
{
    LARGE_INTEGER li;
    if(!QueryPerformanceFrequency(&li))
	std::cout << "QueryPerformanceFrequency failed!\n";

    PCFreq = double(li.QuadPart); // Use seconds

    QueryPerformanceCounter(&li);
    CounterStart = li.QuadPart;
}
double GetCounter()
{
    LARGE_INTEGER li;
    QueryPerformanceCounter(&li);
    return double(li.QuadPart-CounterStart)/PCFreq;
}
const int NUMRESULTS = 10000000;
const int NUMITERATIONS = 100;

int wmain(int argc, char* argv[])
{  
	std::vector<float> nums, results;
	nums.reserve(NUMRESULTS);
	results.reserve(NUMRESULTS);
	for(int i = 0; i < NUMRESULTS; i++)
	{
		nums.push_back(static_cast <float> (rand()) / (static_cast <float> (RAND_MAX/10000.f)) + 0.5f);
		results.push_back(0.f);
	}
	// Get the start time 
	StartCounter();
	for(int iterations = 0; iterations < NUMITERATIONS; iterations++)
	{
		for(int i = 0; i < NUMRESULTS; i++)
		{
			results[i] = glm::inversesqrt(nums[i]);
		}
	}
	double res = GetCounter();
	std::cout << "Time taken for " << NUMITERATIONS << " of " << NUMRESULTS << " floats; Regular Method: " << res << std::endl;

	// Repeat for fastinvsqrt
	StartCounter();
	for(int iterations = 0; iterations < NUMITERATIONS; iterations++)
	{
		for(int i = 0; i < NUMRESULTS; i++)
		{
			results[i] = glm::fastInverseSqrt(nums[i]);
		}
	}
	res = GetCounter();
	std::cout << "Time taken for " << NUMITERATIONS << " of " << NUMRESULTS << " floats; Faster  Method: " << res << std::endl;
	getchar();
}