C / C++ / MFC

//values in vectors are random between -0.5 ... 0.5
#pragma omp parallel for reduction (+: sum)
        for (i = 0; i < N * N; i++) {
                vec3[i] = vec1[i] * vec2[i];
                sum += vec3[i];
        }

sum = 101.759239; // no open mp or single thread
sum = 101.764313; // more than 1 open mp threads

#include <windows.h>
#pragma comment (lib, "winmm.lib")
#include <mmsystem.h>
#include <iostream>
#include <stdio.h>

int main()
{
	int AIDChoise;
	UINT nDevices = waveInGetNumDevs();	// Get No. of devices
	MCI_WAVE_SET_PARMS parms;
	DWORD rc;
	TCHAR ErrMsg[256];
	
	WAVEINCAPS inwcps;
	WAVEOUTCAPS outwcps;

	for (int k=0; k < nDevices; k++)	// Get input audio devices
	{
		waveInGetDevCaps(k,&inwcps,sizeof(inwcps));
		printf(" In devname %d : %s \n",k,inwcps.szPname);
	}
	for (k=0; k < nDevices; k++)	// Get output audio devices
	{
		waveOutGetDevCaps(k,&outwcps,sizeof(outwcps));
		printf(" Out devname %d : %s \n\n",k,outwcps.szPname);

	}
	printf("Please select output device :");
	scanf(" %d",&AIDChoise);
//	getchar();
	  
	switch(AIDChoise)
	{
	case 0:
		printf("0 ~~~~~~~~~");
		parms.wOutput = 0;
		rc = mciSendCommand(0, MCI_SET, MCI_WAVE_OUTPUT, (DWORD)&parms);
		if ( rc != 0 )
			printf("Error Msg : %s \n",mciGetErrorString(rc,ErrMsg,256));
		break;
	case 1:
		printf("1 ~~~~~~~~~");
		parms.wOutput = 1;
		rc = mciSendCommand(1, MCI_SET, MCI_WAVE_OUTPUT, (DWORD)&parms);
		if ( rc != 0 )
			printf("Error Msg : %s \n",mciGetErrorString(rc,ErrMsg,256));
		break;
	default:
		printf("2~~~~~~~~~");
		printf("Invalid command.. \n");
		break;
	}


	return 0;
}

N = 10000;
...
#pragma omp parallel for
for (i = 0; i < N * N; i++)    
    vec3[i] = vec1[i] * vec2[i];
...