ソース：
#include "stdafx.h"
#include <math.h>
using namespace System;

template<typename T> static double calc_norm_and_regulate(int num, T* r, bool regulate){ // <float> for debug.
double norm = 0;
for (int i=0;i<num;i++) norm += (double)r[i] * (double)r[i];
norm = sqrt(norm);
if (regulate) for (int i=0;i<num;i++) r[i] = (T)(r[i]/norm);
return norm;
}

int main(array<System::String ^> ^args)
{
int count = 16;
__int64 inputs_hex[16] = {
0x0000000000000000, 0x0000000000000000, 0x0000000000000000, 0x1fedb1530240aa54,
0x0000000000000000, 0x0000000000000000, 0x0000000000000000, 0x1ff0af0d95025bc3,
0x1fc9353df6af376b, 0x0000000000000000, 0x0000000000000000, 0x0000000000000000,
0x0000000000000000, 0x0000000000000000, 0x0000000000000000, 0x0000000000000000};
double* inputs = (double*)inputs_hex;
double norm = calc_norm_and_regulate(count, inputs, false);
Console::Write(String::Format("{0:F6}, 0x{1:x16}\r\n",norm, *(__int64*)&norm));
// Release build
// 0.000000, 0x1ff68ddfb62221dd from IDE
// 0.000000, 0x1ff68ddfb62221de from command prompt
return 0;
}