frdfun
Apply a function to the frequency response value at each frequency of an
frd
model object
Since R2020a
Syntax
Description
Examples
Apply Functions to Frequency Response Model
For this example, create a frequency response data model by computing the response of a transfer function on a grid of frequencies. For this example, assume a set of 10 frequencies.
H = tf([-1.2,-2.4,-1.5],[1,20,9.1]); w = logspace(-2,3,10); sys = frd(H,w)
sys = Frequency(rad/s) Response ---------------- -------- 0.0100 -0.1648 + 9.847e-04i 0.0359 -0.1644 + 3.508e-03i 0.1292 -0.1597 + 1.130e-02i 0.4642 -0.1294 + 9.857e-03i 1.6681 -0.1058 - 7.515e-02i 5.9948 -0.1883 - 3.050e-01i 21.5443 -0.7004 - 5.495e-01i 77.4264 -1.1337 - 2.623e-01i 278.2559 -1.1946 - 7.725e-02i 1000.0000 -1.1996 - 2.159e-02i Continuous-time frequency response.
sys
is a SISO frequency response data (frd
) model containing the frequency response at 10 frequencies.
Use the frdfun
command to apply the function imag
on the frd
model sys
to obtain the imaginary parts of the frequency response as a function of frequency.
sysImag = frdfun(@imag,sys)
sysImag = Frequency(rad/s) Response ---------------- -------- 0.0100 9.847e-04 0.0359 3.508e-03 0.1292 1.130e-02 0.4642 9.857e-03 1.6681 -7.515e-02 5.9948 -3.050e-01 21.5443 -5.495e-01 77.4264 -2.623e-01 278.2559 -7.725e-02 1000.0000 -2.159e-02 Continuous-time frequency response.
You can also obtain the magnitude of the frequency response of sys
with the abs
function.
sysMag = frdfun(@abs,sys)
sysMag = Frequency(rad/s) Response ---------------- -------- 0.0100 0.1648 0.0359 0.1644 0.1292 0.1601 0.4642 0.1298 1.6681 0.1298 5.9948 0.3585 21.5443 0.8902 77.4264 1.1637 278.2559 1.1971 1000.0000 1.1998 Continuous-time frequency response.
Magnitude of Specific I/O Pairs in MIMO Frequency Response Model
For this example, consider a 2x2 MIMO frequency response model sys
that contains 100 test frequencies for each I/O pair.
Load the frd
object sys
from the MAT-file frdModelMIMO.mat
.
load('frdModelMIMO.mat','sys') size(sys)
FRD model with 2 outputs, 2 inputs, and 100 frequency points.
Define a function to compute the magnitude of the frequency response of the second I/O pair in sys
.
fun = @(h) abs(h(2,2));
Use the frdfun
command to apply the function fun
to the specific I/O pair in sys
.
fsys = frdfun(fun,sys);
Input Arguments
fun
— Function to be applied to frd
model
MATLAB® function
Function to be applied to frd
model, specified as a MATLAB function. The function fun
must accept a single
matrix and return a scalar, vector, or matrix of fixed size across frequency.
sys
— Frequency response data model
frd
model object | genfrd
model object | ufrd
model object
Output Arguments
fsys
— Output frequency response data model
frd
model object
Version History
Introduced in R2020a
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