double OnePoleFilterStereo::getMagnitudeAt(double frequency)
{
  double omega = 2*PI*frequency*sampleRateRec;

  Complex z = expC(Complex(0.0, omega));
  Complex H = getTransferFunctionAt(z);

  return H.getRadius();
}
double LadderFilter::getMagnitudeAt(double frequency, bool withFeedback, bool withMakeUpBoost,
                                   bool withMakeUpGain, int stage)
{
  double omega = 2*PI*frequency / parameters->sampleRate;

  Complex z = expC(Complex(0.0, omega));
  Complex H = getTransferFunctionAt(z, withFeedback, withMakeUpBoost, withMakeUpGain, stage);

  return H.getRadius();
}