Asked by Michael Bernard
on 8 Mar 2012

Hi friends

I was reading a control system book by Saadat. I learned that I can used matlab to convert an ODE to state space phase variable by using the cofficient. The example from the book is below

ai = [2 4 6 8];

k = 10;

[A,B,C] = ode2phv(ai,k)

However, when I tried this example in Matlab, I got an error message saying

'??? Undefined function or method 'ode2phv' for input arguments of type 'double'.

Based on the errpr message, I decided to make an M-file and after running the M-file I got another error message:

Error in ==> ABC2phv at 3 [A,B,C]=ode2phv(a,K)

Therefore, I decided to check if I could find the command or function [A,B,C]=ode2phv(a,K) in my mylab .But when I checked the help, I couldnt find any command or function with [A,B,C]=ode2phv(a,K).

Can anyone help me out? How can I convert any ordinary differential equation to state space? Why is this command [A,B,C]=ode2phv(a,K) not working in my matlab?

I look forward to your help.

Thanks in Advance

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## 1 Comment

## Michael Bernard (view profile)

Direct link to this comment:http://www.mathworks.com/matlabcentral/answers/31582#comment_127128

I finally found solution to the problem. Guys please dont bother anymore. Simply had to write a function file that converts ordinary differential equations to state space phase variables.