measuring execution time for C++ program

[jainyi]

Hi,
I want to calculate execution time for a program computing fibonacci number in C++. I have programmed two functions (one using recursion and other using divide and conquer huristic) to compute fibonnaci number for (n=4,8,16,32,64 ). Now i want to compare these two methods. Though i have used following method to compute execution time but it is not precise as yielding 0 ticker time for n=4,8,16 in both the cases

[code=c]
double execClock(clock _t c1,clock_t c2)
{
double t=clock1-clock2;
double tim=(t*10)/CLOCKS_PER_SEC;
return tim;
}
[/code]

Is there anyother method which is more accurate for lower values of n, i am working in Inet/Windows XP/Dev C++ environment?

While following using recursive method

[code=c]
int fib(int n)
{
if (n <= 1)
return n;
else
return fib(n-1) + fib (n-2);
}
[/code]

i can not compute fibonacci number for n=64, just system gets hanged, CPU usage reaches to 97% for the application, it seems it has struk in the computation

With Regards
Jianyi

[Savage]

Hi,
I want to calculate execution time for a program computing fibonacci number in C++. I have programmed two functions (one using recursion and other using divide and conquer huristic) to compute fibonnaci number for (n=4,8,16,32,64 ). Now i want to compare these two methods. Though i have used following method to compute execution time but it is not precise as yielding 0 ticker time for n=4,8,16 in both the cases

[code=c]
double execClock(clock _t c1,clock_t c2)
{
double t=clock1-clock2;
double tim=(t*10)/CLOCKS_PER_SEC;
return tim;
}
[/code]

Is there anyother method which is more accurate for lower values of n, i am working in Inet/Windows XP/Dev C++ environment?

While following using recursive method

[code=c]
int fib(int n)
{
if (n <= 1)
return n;
else
return fib(n-1) + fib (n-2);
}
[/code]

i can not compute fibonacci number for n=64, just system gets hanged, CPU usage reaches to 97% for the application, it seems it has struk in the computation

With Regards
Jianyi

The most precise method i know is QueryPerformanc eCounter and QueryPerformanc eFrequency which are defined in windows.h.

You use it like:

[CODE="cpp"]LARGE_INTEGER lFreq;
LARGE_INTEGER lTime1;
LARGE_INTEGER lTime2;
long diffTicks;
float diffSecs;

QueryPerformanc eCounter(&lFreq );
QueryPerformanc eFrequency(&lTi me1);
//function
QueryPerformanc eFrequency.(&lT ime2);
diffTicks=lTime 1.QuadPart-lTime2.QuadPart ;//ticks passed
diifSecs=(diffT icks/lFreq.QuadPart) ;//secs passed.[/CODE]

Savage

[jainyi]

Thanks for reply

but it is producing no result; 0 ticks and 0 seconds for each n i.e. 4,8,16, 32

[code=c]
while (quit != 'x')
{
LARGE_INTEGER lFreq;
LARGE_INTEGER lTime1;
LARGE_INTEGER lTime2;
long diffTicks;
float diffSecs;
int i;
for(i=4;i<=66;i =i*2)
{
QueryPerformanc eCounter(&lFreq );
QueryPerformanc eFrequency(&lTi me1);
cout<<fib(i);
QueryPerformanc eFrequency(&lTi me2);
diffTicks=lTime 1.QuadPart-lTime2.QuadPart ;//ticks passed
diffSecs=(diffT icks/lFreq.QuadPart) ;//secs passed.
cout<<" With ticks: " <<diffTicks<< " and seconds: "<<diffSecs<<en dl;
}
cout << endl << " Press x to quit "<<endl;
cin >> quit;
};

=============== =============== =============
int fib(int n)
{
if (n <= 1)
return n;
else
return fib(n-1) + fib (n-2);
}
[/code]

Output is zero ticks and zero seconds for each computed number

Jianyi

[Savage]

My bad,wher you have QueryPerformanc eFrequency put QueryPerformanc eCounter and vise versa.Also subtract time2 from time 1 not vise versa.

Savage

[jainyi]

Though i have got time2 - time1 but notgetting about function calls. Do you mean this way

[code=c]
QueryPerformanc eFrequency(&lTi me1);
QueryPerformanc eCounter(&lFreq );
cout<<fib(i);
QueryPerformanc eFrequency(&lTi me2);
diffTicks=lTime 2.QuadPart-lTime1.QuadPart ;//ticks passed
diffSecs=(diffT icks/lFreq.QuadPart) ;//secs passed.
[/code]


Jianyi

[Savage]

Though i have got time2 - time1 but notgetting about function calls. Do you mean this way

[code=c]
QueryPerformanc eFrequency(&lTi me1);
QueryPerformanc eCounter(&lFreq );
cout<<fib(i);
QueryPerformanc eFrequency(&lTi me2);
diffTicks=lTime 2.QuadPart-lTime1.QuadPart ;//ticks passed
diffSecs=(diffT icks/lFreq.QuadPart) ;//secs passed.
[/code]


Jianyi

No,like this:
[CODE="cpp"]
QueryPerformanc eFrequency(&lFr eq);
QueryPerformanc eCounter(&lTime 1);
//function
QueryPerformanc eCounter(&lTime 2);
.
.
.
.[/CODE]

[jainyi]

Thank you

Now it is fine

Jianyi