The Alternative Csound Reference Manual
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# aresonk

aresonk -- A notch filter whose transfer functions are the complements of the reson opcode.

## Description

A notch filter whose transfer functions are the complements of the reson opcode.

## Syntax

kr aresonk ksig, kcf, kbw [, iscl] [, iskip]

## Initialization

iscl (optional, default=0) -- coded scaling factor for resonators. A value of 1 signifies a peak response factor of 1, i.e. all frequencies other than kcf are attenuated in accordance with the (normalized) response curve. A value of 2 raises the response factor so that its overall RMS value equals 1. (This intended equalization of input and output power assumes all frequencies are physically present; hence it is most applicable to white noise.) A zero value signifies no scaling of the signal, leaving that to some later adjustment (see balance). The default value is 0.

iskip (optional, default=0) -- initial disposition of internal data space. Since filtering incorporates a feedback loop of previous output, the initial status of the storage space used is significant. A zero value will clear the space; a non-zero value will allow previous information to remain. The default value is 0.

## Performance

kr -- the output signal at control-rate.

ksig -- the input signal at control-rate.

kcf -- the center frequency of the filter, or frequency position of the peak response.

kbw -- bandwidth of the filter (the Hz difference between the upper and lower half-power points).

aresonk is a filter whose transfer functions is the complement of reson. Thus aresonk is a notch filter whose transfer functions represents the "filtered out" aspects of their complements. However, power scaling is not normalized in aresonk but remains the true complement of the corresponding unit.

## See Also

areson, atone, atonek, port, portk, reson, resonk, tone, tonek

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