Teilor_26v

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

double cosx(double x)
{
    double n = 1.0;
    double sum = 0.0;
    int i = 1;

    do
    {
        sum += n;
        n *= -1.0 * x * x / ((2 * i - 1) * (2 * i));
        i++;
    } while (fabs(n) > 0.00000000001);

    return sum;
}

int main(int argc, char** argv) {

    double x = 1;
    cout << cosx(x) << endl << cos(x) << endl;

    return 0;
}