fdel

Delete specified data from frequency response data (FRD) models

Syntax

sysout = fdel(sys, freq)


Description

sysout = fdel(sys, freq) removes from the frd model sys the data nearest to the frequency values specified in the vector freq.

Input Arguments

sys	frd model.
freq	Vector of frequency values.

Output Arguments

sysout

frd model containing the data remaining in sys after removing the frequency points closest to the entries of freq.

Examples

Delete Specified Data from Frequency Response Data Model

Create a frequency response data (FRD) model at specified frequencies from a transfer function model.

w = logspace(0,1,10);
sys = frd(tf([1],[1 1]),w)

sys =
 
    Frequency(rad/s)        Response    
    ----------------        --------    
          1.0000        0.5000 - 0.5000i
          1.2915        0.3748 - 0.4841i
          1.6681        0.2644 - 0.4410i
          2.1544        0.1773 - 0.3819i
          2.7826        0.1144 - 0.3183i
          3.5938        0.0719 - 0.2583i
          4.6416        0.0444 - 0.2059i
          5.9948        0.0271 - 0.1623i
          7.7426        0.0164 - 0.1270i
         10.0000        0.0099 - 0.0990i
 
Continuous-time frequency response.

w is a logarithmically-spaced grid of 10 frequency points between 1 and 10 rad/second.

Remove the data nearest 2, 3.5, and 6 rad/s from sys.

freq = [2, 3.5, 6];
sys2 = fdel(sys,freq)

sys2 =
 
    Frequency(rad/s)        Response    
    ----------------        --------    
          1.0000        0.5000 - 0.5000i
          1.2915        0.3748 - 0.4841i
          1.6681        0.2644 - 0.4410i
          2.7826        0.1144 - 0.3183i
          4.6416        0.0444 - 0.2059i
          7.7426        0.0164 - 0.1270i
         10.0000        0.0099 - 0.0990i
 
Continuous-time frequency response.

Note that you do not have to specify the exact frequency of the data to remove. The fdel command removes the data corresponding to frequencies that are nearest to the specified frequencies.

Tips

• Use fdel to remove unwanted data (for example, outlier points) at specified frequencies.

• Use fdel to remove data at intersecting frequencies from frd models before merging them with fcat. fcat produces an error when you attempt to merge frd models that have intersecting frequency data.

• To remove data from an frd model within a range of frequencies, use fselect.