Implementation of Euler Totient function in OpenMP - c++

Question

I am new to OpenMP and I am trying to implement Euler Totient function in OpenMP.
This is my first attempt to code in OpenMP. My goal is to implement it in parallel (fastest, if possible) and then in sequential. After that I calculate the speedup and efficiency.
Below is my code:
/*
============================================================================
Name : 55390_ass3.cpp
Author : Kamil Kamili
Version :
Copyright : Your copyright notice
Description : Euler’s Totient function φ(n) in OpenMP
============================================================================
*/
#include <omp.h>
#include <stdio.h>
#include <stdlib.h>
#include <iostream>
using namespace std;
int eulerTotient(int number)
{
int sNumber = number;
for(int i = 2; i*i <= number; ++i)
{
if(number % i == 0)
{
while(number % i == 0)
{
number /= i;
}
}
}
if(number > 1)
{
sNumber -= sNumber / number;
}
return sNumber;
}
int main (int argc, char *argv[])
{
int nTheads = omp_get_num_threads();
int nMaxThreads = omp_get_max_threads();
printf("Parallel Execution: \n");
double startTimeForParallel = omp_get_wtime();
#pragma omp parallel for
for(int i = 2; i < 10000; i++)
{
printf("φ(%d) = %d\n", i, eulerTotient(i));
}
double parallelTime = omp_get_wtime() - startTimeForParallel;
printf("Sequential Execution: \n");
double startTimeForSequential = omp_get_wtime();
for(int i = 2; i < 10000; i++)
{
printf("φ(%d) = %d\n", i, eulerTotient(i));
}
double sequentialTime = omp_get_wtime() - startTimeForSequential;
double speedUp = sequentialTime/parallelTime;
printf("Parallel Execution Time: ",parallelTime);
printf("Sequential Execution Time: " << sequentialTime);
printf("SpeedUp: "<<speedUp);
return 0;
}
But it does not calculate 'Parallel Time'. Any idea where I am going wrong?
So I edited my code a bit here and there after doing some research. I think I am not using the function omp_get_wtime() correctly.
By Edited Code:
#include <omp.h>
#include <stdio.h>
#include <stdlib.h>
double omp_get_wtime(void);
int eulerTotient(int number)
{
int sNumber = number;
for(int i = 2; i*i <= number; ++i)
{
if(number % i == 0)
{
while(number % i == 0)
{
number /= i;
}
}
}
if(number > 1)
{
sNumber -= sNumber / number;
}
return sNumber;
}
int main (int argc, char *argv[])
{
int nTheads = omp_get_num_threads();
int nMaxThreads = omp_get_max_threads();
printf("Parallel Execution: %f\n");
double parallelTime, endTimeForParallel;
double startTimeForParallel = omp_get_wtime();
#pragma omp parallel for
for(int i = 2; i < 10000; i++)
{
printf("O(%d) = %d\n", i, eulerTotient(i));
}
endTimeForParallel = omp_get_wtime();
parallelTime = startTimeForParallel = endTimeForParallel;
printf("Sequential Execution: \n");
double sequentialTime,endTimeForSequential,startTimeForSequential = omp_get_wtime();
for(int i = 2; i < 10000; i++)
{
printf("O(%d) = %d\n", i, eulerTotient(i));
}
endTimeForSequential = omp_get_wtime();
sequentialTime = startTimeForSequential - endTimeForSequential;
printf("Parallel Execution Time: %f seconds\n", parallelTime);
printf("Sequential Execution Time: %f seconds\n", sequentialTime);
double speedUp = sequentialTime/parallelTime;
printf("SpeedUp: %f\n\n",speedUp);
return 0;
}
The output is simply bizarre. Anyways, here it is:
Parallel Execution Time: 1477476938.765000 seconds
Sequential Execution Time: -0.099000 seconds
SpeedUp: -0.000000
So a very noob mistake: Fixed it
As stated by #Gilles. I fixed my code. Here it is:
/*
============================================================================
Name : 55390_ass3.c
Author : Kamil Kamili
Version :
Copyright : Your copyright notice
Description : Euler Totient's function in C
============================================================================
*/
#include <omp.h>
#include <stdio.h>
#include <stdlib.h>
double omp_get_wtime(void);
int eulerTotient(int number)
{
int sNumber = number;
for(int i = 2; i*i <= number; ++i)
{
if(number % i == 0)
{
while(number % i == 0)
{
number /= i;
}
}
}
if(number > 1)
{
sNumber -= sNumber / number;
}
return sNumber;
}
int main (int argc, char *argv[])
{
int nTheads = omp_get_num_threads();
int nMaxThreads = omp_get_max_threads();
printf("Parallel Execution: %f\n");
double parallelTime, endTimeForParallel;
double startTimeForParallel = omp_get_wtime();
#pragma omp parallel for
for(int i = 2; i < 10000; i++)
{
printf("O(%d) = %d\n", i, eulerTotient(i));
}
endTimeForParallel = omp_get_wtime();
parallelTime = endTimeForParallel - startTimeForParallel;
printf("Sequential Execution: \n");
double sequentialTime,endTimeForSequential,startTimeForSequential = omp_get_wtime();
for(int i = 2; i < 10000; i++)
{
printf("O(%d) = %d\n", i, eulerTotient(i));
}
endTimeForSequential = omp_get_wtime();
sequentialTime = endTimeForSequential - startTimeForSequential;
printf("Parallel Execution Time: %f seconds\n", parallelTime);
printf("Sequential Execution Time: %f seconds\n", sequentialTime);
double speedUp = sequentialTime/parallelTime;
printf("SpeedUp: %f\n\n",speedUp);
return 0;
}
And the output:
Parallel Execution Time: 0.014000 seconds
Sequential Execution Time: 0.095000 seconds
SpeedUp: 6.785746
I still think something is wrong, unless someone tells me otherwise.