Trouble with "pow" function

[camk16]

I know posting a new thread for the same question is frowned upon around here, but I stopped getting replies in the other one, so..

Here is the Question:

Write a program to compute, and later output to the screen, the sum of the series Sn, where Sn is the sum, from i = 1 to n, of ( n + n2 ) / 3. The value n, is entered, via the keyboard, by the user.

Here is what I've got now:

#include <iostream>
#include <math.h>
using namespace std;

int main () {

	int i = 1;
	int n, Sn, sSum = 1;

	cout << "Please enter a value for n: ";
	cin >> n;

    for( i; i <= n; i++)
    {                    
        Sn = ( n + pow(n,2) ) / 3;
        sSum += Sn;
    }
	
	cout << sSum;

    system("PAUSE");
	return 0;
}

I've included <math.h>, but that has not solved the problem of being able to use the pow function.

I'm still having the same issue with this:

Sn = ( n + pow(n,2)) / 3

The "pow" has a squiggly red line under it, and I get an error message:

IntelliSense: more than one instance of overloaded function "pow" matches the argument list

I don't understand.

[PCrumley48]

This doesn't cause the same IntelliSense error in VS Express 2013. Could be that your version can't determine what type variable 2 represents, since it's the only element of your argument list that isn't already declared. Try using 2.0 instead, see what happens.

Three additional comments:

1. Power and division math using int variables will give you some oddball results, since all results will be truncated to integers. i.e. 14/3 = 4.66666. . . in double math, but only 4 in integer form.

2. I think you mean to use i as your variable in line 16, right? If not, then you merely have to multiply (n + pow(n,2)) by n to get the result, and I don't think that's what the question is asking for.

3. Why do you initialize sSum to 1?

[dhayden]

Don't you mean the sum from i= 1 to n of (i+i²)/3? The sum for i=1 to n of (n+n²)/3 is just n(n+n²)/3

To avoid overflow and rounding errors, make i and Sn doubles instead of ints.