MATLAB: Multiple periodograms

MATLABperiodogram

I have some data in vector 'x'. I can compute a periodogram easily enough by
y=x;
[Pxx,w] = pwelch(y);
Great, all is good, BUT if I want to transform 'x' to absolute values and compute the periodogram for this as well, like
y=(x);
y2=abs(x);
[Pxx,w] = pwelch(y);
[Pxx,w] = pwelch(y2);
Well does not really work, I am just re-writing [Pxx,w] !
so I try like
y=(x);
y2=abs(x);
[Pxx,w] = pwelch(y);
[2Pxx,2w] = pwelch(y2);
But then I have a syntax error as [2Pxx,2w] is not allowed, I must use 'Pxx' and 'w'.
How can I this?

Best Answer

Just do
    [Pxx2,w] = pwelch(y2);
Or any legal variable name. MATLAB variable names must start with a letter followed by up to 30 letters, digits, or underscores. It is also case sensitive.
Related Question