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Topic: iddata irregular sampling time
Replies: 2   Last Post: Sep 13, 2010 1:07 PM

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Gabriyel

Posts: 6
Registered: 2/26/09
Re: iddata irregular sampling time
Posted: Sep 13, 2010 1:07 PM
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Hi Greg,

Thanks for posting the solution. I've also read it from the Matlab documentation however, I still face a problem. Matlab keeps complaining that Ts needs to be specified even when I used the example given directly, i.e.

data = iddata(y,u,Ts,[],'SamplingInstants',TimeVector)

I'm sure I have all the variables correct except Ts because I cannot specify any scalar value for it since the interval is irregular. Furthermore, Matlab says Ts will be interpreted automatically as []. Why then does it still complain?

Appreciate any advice.

Best regards,
Gab


Greg Heath <heath@alumni.brown.edu> wrote in message <bd8f3075-728c-4cba-8356-5553c7ce4fb1@m37g2000yqf.googlegroups.com>...
> On Feb 26, 9:24 am, Keith <kdt...@gmail.com> wrote:
> > Hi all,
> > I am trying to create a iddata variable in Matlab with inputs/outputs that I already have. The sampling interval, however, is irregular. When I put
> >
> > load('y_u')
> > load('time')
> > z=iddata(y_u,u,[])
> >
> > (the [] is to denote an irregular ts), the following message appears:
> >
> > "If the value of the "Ts" property is empty, a non-empty value for the "SamplingInstants" property must
> > be specified."
> >
> > Therefore, I put the following:
> >
> > load('y_u')
> > load('time')
> > z=iddata(y_u,u,[], 'SamplingInstances',time)

>
> The documentation states:
>
> BEGIN QUOTE
> For nonuniformly sampled data, specify Ts as [], and set the value of
> the SamplingInstants property as a column vector containing individual
> time values.
> For example:
>
> data = iddata(y,u,Ts,[],'SamplingInstants',TimeVector)
>
> Where TimeVector represents a vector of time values.
>
> END QUOTE
>
> Although the example doesn't seem to follow the directions,
> considering this may help you figure it out.
>
> Hope this helps.
>
> Greg




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