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### Highlights from Bode plot with asymptotes

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4.4 | 12 ratings Rate this file 26 Downloads (last 30 days) File Size: 3.4 KB File ID: #10183 Version: 1.2

# Bode plot with asymptotes

### Trond Andresen (view profile)

28 Feb 2006 (Updated )

Bode plot with asymptotes

File Information
Description

The function asymp() corresponds to bode(), but it also plots asymptotes for the magnitude and phase graphs. Phase asymptotes are vertical.
asymp() only accepts monovariable transfer functions.
If the transfer function also has a time delay, the time delay is ignored
for the phase asymptotes.
asymp() may be called in two ways only, asymp(h), or asymp(h,wmin,wmax).

Required Products Control System Toolbox
MATLAB release MATLAB 8.6 (R2015b)
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Comments and Ratings (17)
21 Mar 2016 Trond Andresen

### Trond Andresen (view profile)

I am the author of this function. It works also for the counter-examples given here by other commenters.

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09 Mar 2016 Aim Dulay

### Aim Dulay (view profile)

27 May 2015 Rafael Crepaldi

### Rafael Crepaldi (view profile)

23 Jun 2012 Marcos Gonzalez

### Marcos Gonzalez (view profile)

24 Apr 2012 Yngve

### Yngve (view profile)

The asymptotes does not work for angles in this bandstop-filter:

>> H = tf([1 0 4000.*16000],[1 4000+16000 4000.*16000])

Transfer function:
s^2 + 6.4e007
-----------------------
s^2 + 20000 s + 6.4e007

>> asymp (H)

(Maybe because of the sudden 180 degree phase shift at the bandstop frequency)

Other than that, the program is wonderful <3

06 Jan 2011 Robert Stengel

### Robert Stengel (view profile)

It doesn't work with this simple test:
f11 = -1.2794;
f12 = -7.9856;
f22 = -1.2709;
F = [f11 f12;1 f22];
G = [-f12;0];
Hx = [1 0];
B22 = inv(-Hx*inv(F)*G)
sys = ss(F, G*B22, Hx,0);
figure
step(sys), grid
figure
bode(sys),grid
figure
asymp(sys)

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12 Mar 2010 Moussab Bennehar

### Moussab Bennehar (view profile)

12 Mar 2010 Moussab Bennehar

### Moussab Bennehar (view profile)

You're a Geeeeeeeeeeenius
really, great m file
thanx

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17 Oct 2009 Robert

### Robert (view profile)

i need help...it keeps saying error at asymp at 19

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12 May 2008 Nabil al-hadawy

******* Thank you **********
This is function (asymp.m) very nice

09 Apr 2008 John babs

great stuff. thanks!

04 Dec 2007 Joseph Birbiglia

Very good, but there are errors with the following transfer function:

G(s) = (s^2+1)/(s*(s^2+4))

---------
??? Error using ==> colon
Maximum variable size allowed by the program is exceeded.

Error in ==> asymp at 147
set(get(gcf, 'CurrentAxes'),'YTick',magmin:ydelta:magmax);
----------------

12 Nov 2007 Trung Duong

It's work. Nice job

04 Apr 2007 Trond Andresen

I am the author of asymp( ).The problem reported by Anton Cervin has now been fixed. Please tell me if problems still remain.

Comment only
29 Sep 2006 Anton Cervin

It does not seem to work.

>> G = (s+1)/(s*(s+10))

Transfer function:
s + 1
----------
s^2 + 10 s

>> asymp(G)
??? Error using ==> axes
Invalid object handle.

Error in ==> asymp at 120
axes(h);

18 Jun 2006 Zain Gurraya
02 Mar 2006 Jiro Doke

A similar submission:

I would appreciate a more comprehensive help text at the top. The code is documented pretty well. There are some coding styles that could be better (i.e. the while loops). Since you are plotting the asymptotes, maybe the function could return the break frequencies and the corresponding slopes of the asymptotes. It can have the same behavior as BODE, in which if there are no output arugments, then it would create a plot, and if there are outputs, then it wouldn't create a plot.

16 Mar 2007

Fix error: A reviewer pointed out that a certain transfer function didn't work with the current version.

18 Mar 2016 1.2

Compatible with Matlab 2015

18 Mar 2016 1.2

Fixed for compatibility with newer Matlab versions