# cheb2ord

Chebyshev Type II filter order

## Description

## Examples

## Input Arguments

## Output Arguments

## Algorithms

`cheb2ord`

uses the Chebyshev lowpass filter order prediction formula
described in [1]. The function performs
its calculations in the analog domain for both analog and digital cases. For the digital case,
it converts the frequency parameters to the *s*-domain before the order and
natural frequency estimation process, and then converts them back to the
*z*-domain.

`cheb2ord`

initially develops a lowpass filter prototype by
transforming the stopband frequencies of the desired filter to 1 rad/s (for low- and highpass
filters) and to -1 and 1 rad/s (for bandpass and bandstop filters). It then computes the
minimum order and natural frequency required for a lowpass filter to match the stopband
specification exactly when using the values in the `cheby2`

function.

## References

[1] Rabiner, Lawrence R., and Bernard
Gold. *Theory and Application of Digital Signal Processing.* Englewood
Cliffs, NJ: Prentice-Hall, 1975.

## Extended Capabilities

## Version History

**Introduced before R2006a**