// check wether self.freq is part of SteeringVector.f
freqInSteerObjFreq = isclose(array(self.steer_obj.f), self.freq)
if freqInSteerObjFreq.any():
freqInd = flatnonzero(freqInSteerObjFreq)
else:
warn("PointSpreadFunction.freq was appended to PointSpreadFunction.steer_obj.f, "\
"as it was not an element of the original list! "\
"You should check possible implications on beamformer results, etc.", Warning, stacklevel = 2)