for (int i = 0; i < N; i++) {
        for (int j = 1; j < k+1; j++) {
            suma += ( (1.0 / (2.0 * k - 1)) * sin((2.0 * k - 1.0) * 2.0 * PI * i * f) );
        }
        x[i] = ( 4.0 / PI ) * suma;
        suma = 0;
}