# Fitting filters and transfer functions models¶

Deprecated since version 1.2.71: The package identification will be combined with the package deconvolution and renamed to model_estimation in the next major release 2.0.0. From version 1.4.1 on you should only use the new package Model estimation instead.

The package for now still contains the following modules:

• PyDynamic.identification.fit_filter: least-squares fit to a given complex frequency response

• PyDynamic.identification.fit_transfer: identification of transfer function models

## Fitting filters to frequency response¶

Deprecated since version 1.2.71: The package identification will be combined with the package deconvolution and renamed to model_estimation in the next major release 2.0.0. From version 1.4.1 on you should only use the new package Model estimation instead.

This module contains several functions to carry out a least-squares fit to a given complex frequency response.

This module for now still contains the following functions:

• LSIIR(): Least-squares IIR filter fit to a given frequency response

• LSFIR(): Least-squares fit of a digital FIR filter to a given frequency response

## Identification of transfer function models¶

Deprecated since version 1.2.71: The package identification will be combined with the package deconvolution and renamed to model_estimation in the next major release 2.0.0. From version 1.4.1 on you should only use the new package Model estimation instead.

The module PyDynamic.identification.fit_transfer contains several functions for the identification of transfer function models.

This module for now still contains the following function:

• fit_sos(): Fit second-order model to complex-valued frequency response