[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Bode question

From: Doug Stewart
Subject: Re: Bode question
Date: Wed, 26 Mar 2003 20:55:50 -0500
User-agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.2.1) Gecko/20021130

Moorman wrote:
 OK, this is a question born of ignorance. So laugh
 at it, chuckle at my lack of knowledge. But, answer
 it :-)

 I have never used MatLab for any work. I recently
 inherited some MatLab code. I downloaded the Windows
version of Octave to see if the code would run. (v 2.1.36)

 Everything is fine until the bode function is
 invoked. I then get a message that the first
 argument must be a system data structure.

 The bode command in the Matlab program is
 bode (a, b, c)

 a is a 180 x 1 matrix of real numbers
 b is a 180 x 1 matrix of complex
 c is a 180 x 1 matrix of complex

 I found some great help on using both matlab and
 octave, including particular invocations of bode
in matlab. For example, one page suggested the following test:

 num = [0.2 0.3 1]
 den1 = [1 0.4 1]
den2 = [1 0.5]
 den = conv(den1, den2)
 w = logspace(-1, 1, 50)

[mag, phase] = bode(num, den, w)
 When I try this, same error about the
 needing to be a system data structure.
Now, I read the material on the internal system data structure, but I am unsure what to do :-(

Again, I apologize for this question. I actually feel so lacking of knowledge in this area that I feel I am probably not even asking a reasonable question. But, I had to try something before
 I go back to beating my head against the
 wall :-(

Thanks for any insight you can shed or pointers to what to read.

Thanks, Kenny

what you must do is:

[mag, phase] = bode(sys1, w)

Doug Stewart

Octave is freely available under the terms of the GNU GPL.

Octave's home on the web:
How to fund new projects:
Subscription information:

reply via email to

[Prev in Thread] Current Thread [Next in Thread]