I have a matrix of 4095 by 4. i need to divide it into submatrices of 117 by 1.

How can I do this using for loop? I mean I have to select first 117 rows and 1st column then first 117 rows and 2nd column, then first 117 rows and 3rd column and then 1st 117 rows and 4th column. after that repeat this for next 117 rows and so on uptill 4095 rows.

Answer 1

[Walter Roberson]

Baserow = (column-1) * 117;
Subset = YourImage(Baserow+(1:117),column, :) ;

[Sajid Sarwar]

@Walter Roberson sir, how i will define column in above code lines?

[Walter Roberson]

 Baserow = (FirstForLoopVariableName-1) * 117;
 for SecondForLoopVariableName = 1:4
   Subset = YourImage(Baserow+(1:117),SecondForLoopVariableName, :) ;
  DoSomethingWithSubset(Subset);
  end

[Sajid Sarwar]

@Walter Roberson sir, thank you very much. kindly tell me how to combine these subsets in one matrix. for example I'm working on following lines.

st=rand(9945,4)
for n=1:85
  Baserow = (n-1) * 117;
  for n1 = 1:4
    Subset = st(Baserow+(1:117),n1, :)
    txSig = ofdmMod(Subset);                      
    y = awgn(txSig, SNR(k));
    sigRx = ofdmDemod(y);
   end
end

I'm getting 340 sub matrices of "Sigtx" of 117 by 1. How to combine them in a single matrix?

thanku.

[Walter Roberson]

st=rand(9945,4)
for n=1:85
  Baserow = (n-1) * 117;
  for n1 = 1:4
    Subset = st(Baserow+(1:117),n1, :)
    txSig(n, n1, :) = ofdmMod(Subset);                      
    y = awgn(txSig(n, n1, :), SNR(k));
    sigRx(n, n1, :) = ofdmDemod(y);
   end
end

After that you might want to reshape() txSig and sigRx, and you might want to permute() them before you reshape. How do you want the outputs for a given n, n1 to be positioned in memory relative to the outputs for (n+1),n1 and n,(n1+1) ?

[Sajid Sarwar]

txSig(n, n1, :) = ofdmMod(Subset);

by this line I'm getting txSig in 3 dimensions whereas I need 2D data for further use in y = awgn(txSig, SNR(k));

and sigRx = ofdmDemod(y);

[Walter Roberson]

You do not need 2D data for awgn. You might need a row vector for ofdmDemod though.

st=rand(9945,4)
for n=1:85
  Baserow = (n-1) * 117;
  for n1 = 1:4
    Subset = st(Baserow+(1:117),n1, :)
    txSig(n, n1, :) = ofdmMod(Subset);                      
    y = awgn(txSig(n, n1, :), SNR(k));
    sigRx(n, n1, :) = ofdmDemod(y(:).');
   end
end