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Re: Error exploring a Matlab example
From: |
jmb |
Subject: |
Re: Error exploring a Matlab example |
Date: |
Tue, 21 Oct 2014 17:57:12 -0400 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.1.2 |
On 10/21/2014 04:34 PM, James Sherman Jr. wrote:
> On Tue, Oct 21, 2014 at 2:08 PM, jmb <address@hidden> wrote:
>> Hello,
>>
>> I am toying with a Matlab for control loop example that I found here:
>>
>> http://www.mathworks.com/help/control/examples/temperature-control-in-a-heat-exchanger.html
>>
>> The problem is I get:
>> Gp = exp(-theta*s)/(1+tau*s)
>> error: exp: not defined for class
>>
>> But alternates like:
>> octave>>Gp = 1/(1+tau*s)
>> Transfer function 'Gp' from input 'u1' to output ...
>> 1
>> y1: ----------
>> 21.3 s + 1
>> Continuous-time model.
>>
>> octave>>Gp = (-theta*s)/(1+tau*s)
>> Transfer function 'Gp' from input 'u1' to output ...
>> -14.7 s
>> y1: ----------
>> 21.3 s + 1
>> Continuous-time model.
>> Do work...
>>
>> It appears that the exp() function is not able to handle a (Laplace
>> Transform) transfer function variable. Any ideas, thoughts or help
>> would be very much appreciated.
>>
>> Again the relevant version info:
>> octave:2> version 3.8.1
>> octave:3> pkg list
>> Package Name | Version | Installation directory
>> ----------------+---------+-----------------------
>> io *| 2.2.4 | /home/.../octave/io-2.2.4
>>
>> lsb_release -a
>> Description: Ubuntu 12.04.5 LTS
>>
>> uname -a
>> Linux ... 3.5.0-55-generic #82~precise1-Ubuntu SMP x86_64 x86_64
>> x86_64
>> GNU/Linux
>>
>> Regards, JMB
>>
>>
>> _______________________________________________
>> Help-octave mailing list
>> address@hidden
>> https://lists.gnu.org/mailman/listinfo/help-octave
> Hi JMB,
>
> You linked to a example in MATLAB's control toolbox. So, as a first
> guess, I'd try installing the control package:
> http://octave.sourceforge.net/control/
> to see if that helps.
>
> James Sherman
>
Hello James,
Thank you for your suggestion. I am at fault for not having shown
control as being loaded, because I just copied the version information
from my previous post. Yes I do have it loaded:
octave:1> pkg list
Package Name | Version | Installation directory
----------------+---------+-----------------------
actuarial *| 1.1.0 | /home/.../octave/actuarial-1.1.0
audio *| 1.1.4 | /home/.../octave/audio-1.1.4
communications | 1.2.0 | /home/.../octave/communications-1.2.0
control *| 2.6.5 | /home/.../octave/control-2.6.5
and actually is loaded by default and yet I get the same error message.
Regards, JMB