Undefined function periodgram for input arguments of type double?

Hello!

I am trying to use the function periodgram in order to plot a timeseries (x) which was an 100x4 matrix.

Fs = 400
x = x(:,1)
[PSD, normalized_frequency] = periodgram(x,Fs)

I am getting the following error:

Error in periodogram (line 202)
if any([signal.internal.sigcheckfloattype(x1,'single','periodogram','X')...
 
Undefined function 'periodgram' for input arguments of type 'double'.
      
end

when I went to go look at the documentation, I got this message:

Input X in periodogram must be double/single, instead it was char.

Which seems to be giving mixed messages.

I tried the following:

%1) converting double to single
x = x(:,1);
x = single(x);
[PSD, norm_frequency] = periodgram(x, Fs)

Do you have any suggestions?

Thanks so much.

Answer 1

[Star Strider]

It would be nice to know what ‘x’ is.

If it is a table, the reference should be:

x{:,1}

(note the curly braces {}) instead.

[nines]

hello!

here is a picture of x. It is a table I believe!

I used brackets instead but am now getting an error that the brackets are not supported with variables of this type.

x = x{:,1};
[PSD, norm_frequency] = periodgram(x, Fs)

Thanks for all of your help!

[Star Strider]

My pleasure!

Assign it to something with a different name:

xv = x{:,1};

[PSD, norm_frequency] = periodgram(xv, Fs)

The error probably refers to the problem of having ‘x’ on both sides of the assignment.

.

[nines]

hmm unfortunately I just checked and changed the variables and am still getting the same error that brace indexing is not supported for variables of this type.

physio_timeseries = phys{:,1};
[PSD, norm_frequency] = periodgram(physio_timeseries, Fs)

thanks so much!

[Star Strider]

As always, my pleasure!

I would have to know what type variable it is, and preferably have it to experiment with.

[nines]

I would just like to send along a huge thank you -- honestly, my thesis would be not nearly where it is without your help and all of the nice senior people at matlab answers. I was reading a lot of your answers on matlab and am just so impressed and so grateful at all of your time and dedication to this; thanks a ton. :)

[Star Strider]

As always, my (our) pleasure!