why the bode function doesn't work?

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jia ming chen
jia ming chen 2015-1-19
回答： Felix Götze 2016-2-9
this is my problem...
>> s=tf('s')
s =
s
Continuous-time transfer function.
>> g=1/(1+s)
g =
1
-----
s + 1
Continuous-time transfer function.
>> bode(g) Error using DynamicSystem/bode (line 97) Index exceeds matrix dimensions.
can anyone solve it?

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回答（3 个）

Felix Götze
Felix Götze 2016-2-9
Hi,
I had the same Problem. In my case the error occured because I had a figure window open. If you have an open figure close it and try the command again it should work properly now.
Youssef Khmou
Youssef Khmou 2015-1-19
编辑：Youssef Khmou 2015-1-19
The description is correct and the code is working correctly,try clearing the existing variables
clear all;
s=tf('s'); g=1/(1+s); bode(g);
  2 个评论
jia ming chen
jia ming chen 2015-1-19
no, it still doesn't work. i think is a problem of che code or my matlab version... the system says that there is a problem in the line 97 of the code , but I've never touched the source of the code.
Youssef Khmou
Youssef Khmou 2015-1-20
编辑：Youssef Khmou 2015-1-20
Bode function contains the following code from line 92 through 100
92 case 3
93 % Transfer function form with time vector
94 if size(a,1)>1,
95 % SIMO syntax
96 a = num2cell(a,2);
97 den = b;
98 b = cell(size(a,1),1);
99 b(:) = {den};
100 end

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Andreas Goser
Andreas Goser 2015-1-20
Can you verify the output of
which bode -all
Youe should get something like this:
C:\Program Files\MATLAB\R2014b\toolbox\control\ctrlobsolete\bode.m
C:\Program Files\MATLAB\R2014b\toolbox\shared\controllib\engine\@DynamicSystem\bode.m % DynamicSystem method
Is not, there maybe another function or variable shadowing the bode function you want.
  2 个评论
Lukas Kurmann
Lukas Kurmann 2015-3-18
Hi all,
as stupid it may sound, I have the same problem - bode is not working (any more). Checked possible shadowing, but it seems not the case... Maybe my path is too long (C:\Projects\FHNW\Vorlesungen\HT FHNW\LF Medizinische Automatisierungssysteme\2015FS\03.Unterrichtsvorbereitung\20150316 WK12 - Block 9 - Diskrete Regler\MATLAB')?
Run currently the 8.3.0.532 (R2014a) version, but shall I update to the R2015a? Thx for an answer! BR Lukas
Andreas Goser
Andreas Goser 2015-3-19
This user had a different error message. The solution was a compatibility with a 3rd part toolbox. Once this was removed from the path, BODE was working fine.

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