MATLAB: How to find auto-correlation of a matrix size 12×256

auto-correlation

working on auto-correlation functions and PSD.

Have a look at corrmatx function.

X = corrmtx(x,m,'method');

Ref: https://ch.mathworks.com/help/signal/ref/corrmtx.html

Before plot, put there lines and tell us what it says

size(t)  % Don't use a semicolon



size(pv)  % Don't use a semicolon
class(t)  % Don't use a semicolon
class(pv)  % Don't use a semicolon

And I don't see any autocorrelation going on, just reading data from a workbook and plotting it.

Do you mean you want to compute autocorrelation for each column? If so, you can always use a for loop to do that, e.g.,

x = ones(10,2);
r = zeros(2*size(x,1)-1,size(x,2);
for m = 1:size(x,2)
  r(:,m) = xcorr(x(:,m));
end

Or if you don't mind dealing with cell arrays, you can always do

x = ones(10,2);
r = arrayfun(@(n)xcorr(x(:,n),1:size(x,2),'UniformOutput',false);