tf

Transfer function

Syntax

[B,A] = tf(npFilter)

[B,A,B2,A2] = tf(npFilter)

Description

[B,A] = tf(npFilter) returns the vector of numerator coefficients, B, and the vector of denominators, A, for the equivalent transfer function corresponding to the notch filter.

[B,A,B2,A2] = tf(npFilter) also returns the vector of numerator coefficients, B2, and the vector of denominator coefficients, A2, for the equivalent transfer function corresponding to the peak filter.

Examples

Determine Transfer Function of Notch Peak Filter

Create a dsp.NotchPeakFilter System object™. Obtain the coefficients of the transfer function corresponding to the notch and peak filters.

notchpeak = dsp.NotchPeakFilter;
[Bnotch,Anotch,Bpeak,Apeak] = tf(notchpeak)

Bnotch = 1×3

    0.8633   -0.0000    0.8633

Anotch = 1×3

    1.0000   -0.0000    0.7265

Bpeak = 1×3

    0.1367         0   -0.1367

Apeak = 1×3

    1.0000   -0.0000    0.7265

Bnotch and Anotch are the vectors of numerator and denominator coefficients for the equivalent transfer function corresponding to the notch filter. Bpeak and Apeak are the vectors of numerator and denominator coefficients for the equivalent transfer function corresponding to the peak filter.

Input Arguments

npFilter — Notch peak filter object

dsp.NotchPeakFilter

Notch peak filter object, specified as a dsp.NotchPeakFilter object.

Output Arguments

B — Numerator coefficients of notch filter

vector

Numerator coefficients for the equivalent transfer function corresponding to the notch filter, specified as a vector.

Data Types: double

A — Denominator coefficients of notch filter

vector

Denominator coefficients for the equivalent transfer function corresponding to the notch filter, specified as a vector.

Data Types: double

B2 — Numerator coefficients of peak filter

vector

Numerator coefficients for the equivalent transfer function corresponding to the peak filter, specified as a vector.

Data Types: double

A2 — Denominator coefficients of peak filter

vector

Denominator coefficients for the equivalent transfer function corresponding to the peak filter, specified as a vector.

Data Types: double

Version History

Introduced in R2014a

R2024a: Support for normalized frequencies

In the dsp.NotchPeakFilter object, you can now specify the 3-dB bandwidth and center frequency values in normalized frequency units (0 to 1). To enable this functionality, set the NormalizedFrequency property of the object to true.