CPPForSchool.com: Flow of Control Set 3: Assignment 3

3. Write a program to compute the cosine of x. The user should supply x and a positive integer n. We compute the cosine of x using the series and the computation should use all terms in the series up through the term involving xⁿ

cos x = 1 - x²/2! + x⁴/4! - x⁶/6! ...


It is quite frustrating to run into the unknown and unable to decipher my lack of comprehension to the subject at hand.  Although, I understand conceptually what cos x is, it does not translate to C++.  Although, things may be different if I am able to use the math library in C++, this assignment is supposed to be answered utilizing loops.  Like the prior assignment, I will have to omit any code and simply post the sample source code provided by CPPForSchool.

#include<iostream>
using namespace std;

int main()

{

 int i,j,n,fact,sign=-1;
 float x, p,sum=0;

 cout<<"Enter the value of x : ";
 cin>>x;
 cout<<"Enter the value of n : ";
 cin>>n;


 for(i=2;i<=n;i+=2)
 {
                p=1
  fact=1;
  for(j=1;j<=i;j++)
  {
   p=p*x;
   fact=fact*j;
  }
  sum+=sign*p/fact;
  sign=-1*sign;
 }
 cout<<"cos "<<x<<"="<<1+sum;
 return 0;
}