How to loop this over the columns?

Hello, I currently have a code that deals with some indicator and signaling as follows for one row of data indexed by the variable idx. The code is as follows:

syms = ['A' 'B' 'C' 'D' 'TU']; %%Matrix of size (1xN) containing Strings
tday = rand(2000,1); %%Matrix that I want idx to pull values out of which corresponds to the string matched
cl = rand(2000, 5) %%%%Another Matrix that I want idx to pull values out of which corresponds to the string matched
idx=strmatch('TU', syms, 'exact');
tday=tday(:, idx);
cl = cl(:,idx); 

lookback=30
holddays=30;

longs=cl > backshift(lookback, cl)  ; %%For Backshift Function Please see Function Defined Below.
shorts=cl < backshift(lookback, cl) ;

pos=zeros(length(cl), 1);

for h=0:holddays-1
        long_lag=backshift(h, longs);
        long_lag(isnan(long_lag))=false;
        long_lag=logical(long_lag);

        short_lag=backshift(h, shorts);
        short_lag(isnan(short_lag))=false;
        short_lag=logical(short_lag);

        pos(long_lag)=pos(long_lag)+1;
        pos(short_lag)=pos(short_lag)-1;
  end

ret=(backshift(1, pos).*(cl-backshift(1, cl))./backshift(1, cl))/holddays;

ret(isnan(ret))=0;
idx=find(tday==20070103);
% idx=1;

cumret=cumprod(1+ret(idx:end))-1;

plot(cumret);

This code currently works for pulling one matrix out... How would I do it if I want to iterate over all the columns for all the strings contained in syms? What would be the most efficient way to get this done and would there be a way to not specify any string matches instead since I want to do it for all the symbols contained in the matrix strings ? I know I am supposed to do a nested loop but it says that there was an issue with my dimension (I think it may have to do with the fact that h is indexed at 0, which I am also kind of confused about.

As a side note, the function above defined as backshift has the following code:

function y=backshift(day,x)
% y=backshift(day,x)
assert(day>=0);
y=[NaN(day,size(x,2), size(x, 3));x(1:end-day,:, :)];
end

Thanks

Answer 1

[Walter Roberson]

Your line

syms = ['A' 'B' 'C' 'D' 'TU']

creates

syms = 'ABCDTU'

You need a cell array of strings,

syms = {'A' 'B' 'C' 'D' 'TU'}

[Putsandcalls]

Oops sorry about that, I meant that it was a cell array when I was creating the example, but what would be your recommended advice ? Im a bit unsure about why the indexing is 0, I can just replace it with 1 and do a nested loop over the columns and removing the IDX right ?

Thanks