2 outputs from a function (pwelch) into a cell array

I am using the function pwelch to calculate the PSD of my signal. Currently, I am doing
[pxx,f] = pwelch(data,50000,[],[],Fs);
for a single window value. However, I need to test several window values so I created
pwelchvalues= [10000 50000 100000 250000 500000 750000];
But now I don't know how to modify the left side of the equation. I cannot use just
[pxx,f] =
because the pxx's and f's of each value will be of different length. I have tried for loops, cellfun and several combinations like
[pxx{:},f{:}] = pwelch(data, pwelchvalues,[],[],Fs);
but I keep getting error like: "Cell contents assignment to a non-cell array object." or "Error: Unbalanced or unexpected parenthesis or bracket."
What is the correct syntax?

 Akzeptierte Antwort

Walter Roberson
Walter Roberson am 29 Jul. 2017
[pxx, f] = arrayfun(@(W) pwelch(data, W, [], [], 2048), pwelchvalues, 'uniform', 0);

4 Kommentare

ErikaZ
ErikaZ am 29 Jul. 2017
Bearbeitet: ErikaZ am 29 Jul. 2017
I don't understand when and how to use arrayfun and cellfun. For example, now I need to plot the equivalent of
semilogx(f,20*log10(pxx));
In other words, I want to plot all 4 columns of each pxx (total of 24 PSDs) with their respective f in a single figure.
X = f;
Y = cellfun(@(p) 20*log10(p),pxx,'uniform', 0);
XY = [X(:); Y(:)] ;
semilogx(XY{:})
You might want to consider just using a loop.
ErikaZ
ErikaZ am 31 Jul. 2017
I ended up using a for loop because the top code didn't quite work even with some changes. Thanks!
X = f;
Y = cellfun(@(p) 20*log10(p),pxx,'uniform', 0);
XY = [X(:).'; Y(:).'] ;
semilogx(XY{:})

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