Ряд Тейлора для ln ((x + 1) / (x - 1))

#include <iostream>
#include <iomanip>

using namespace std;

void h_line(streamsize);
unsigned series(const double, const double, double &);

int main() {
    double x_beg, x_end, dx, arg = 0, eps;
    cout << "x_beg?.. "; cin >> x_beg;
    cout << "x_end?.. "; cin >> x_end;
    cout << "dx?.. "; cin >> dx;
    cout << "exp?.. "; cin >> eps;

    if (x_end > x_beg && dx > 0 && eps > 0 && eps >= 1e-14) {
        unsigned q;
        unsigned char v = 179;
        streamsize lr = 9, c = 19, tb = lr * 2 + c + 10, acc = 16;

        cout << "\n\t\tTITLE TABLE\n";
        h_line(tb);
        cout << v << ' '
             << setw(lr) << "Argument"
             << ' ' << v << ' '
             << setw(c)  << "Function"
             << ' ' << v << ' '
             << setw(lr) << "Quantuty"
             << ' ' << v << endl;
        h_line(tb);

        for (double x = x_beg; x <= x_end + dx / 2; x += dx) {
            if (abs(x) > 1) {
                q = series(x, eps, arg);

                cout << v << ' '
                     << setw(lr) << x
                     << ' ' << v << ' '
                     << setw(c) << setprecision(acc) << arg
                     << ' ' << v << ' '
                     << setw(lr) << q
                     << ' ' << v << endl;
            } else cout << v << ' '
                        << setw(lr) << x
                        << ' ' << v << ' '
                        << "\t Argument error!\a"
                        << setw(acc - 2) << ' ' << v << endl;
            h_line(tb);
        }
    } else cout << "\tError!\a\n";

    cin.get(); cin.get();
    return 0;
}
void h_line(streamsize _h) {
    if (_h > 80 ) _h = 80;
    unsigned char h = 196;
    for (streamsize n = 0; n < _h; n++) cout << h;
    cout << endl;
}

unsigned series(const double _x, const double _exp, double & _arg) {
    unsigned n = 0;
    int dx = 1;
    double arg = log((_x + 1) / (_x - 1));
    double sum = 0, temp = arg * 2;

    while (abs(abs(temp) - abs(arg)) > _exp) {
        ++n;
        sum += 1 / (dx * pow(_x, dx));
        temp = 2 * sum;
        dx += 2;
    }

    _arg = temp;
    return n;
}