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IIR comb notch or peak filter

`[`

returns a digital notching filter with order `num`

,`den`

] = iircomb(`n`

,`bw`

)`n`

and with the width of
the filter notch at `-3`

dB set to `bw`

, the filter
bandwidth.

For the notching filter, the transfer function takes the form:

$$H(z)=b\frac{1-{z}^{-n}}{1-\alpha {z}^{-n}}$$

where *α* and *b* are positive scalars and
*n* is the filter order or the number of notches in the filter minus
1.

[1] Orfanidis, S.J.,
*Introduction to Signal Processing*, Englewood Cliffs, New Jersey:
Prentice-Hall, 1996.

`firgr`

| `iirnotch`

| `iirparameq`

| `iirpeak`