#include <iostream>
#include <cmath>

using namespace std;

double ch(double x, double eps = 1e-7)
{
    double s = 1, t = 1;
    x *= x;
    for(int k = 1; abs(t) > eps; k += 2)
        s += t *= x/k/(k+1);
    return s;
}

int main(int argc, char * argv[])
{
    for(double x = 0; x <= 1; x += 0.1)
        cout << x << "  " << ch(x) << "  " << (exp(x)+exp(-x))/2 << endl;

}