For loop not saving answers into matrix.

Hi all,

I'm sure I've done something silly, but I can't work out why my code isn't working. Hopefully a fresh pair of eyes will help.

I'm trying to perform a moving correlation by specifying the index locations within a matrix for the correlation to be performed on. This then cycles through the for loop to give me answers for my whole matrix.

BUT! It's not saving each value into my specified matrix, and my output (MIChinacorr) is just a NaN matrix.

I know that the corr code works, because when I manually say k=1, I get an answer.

What am I doing wrong?

%Select moving window

window_size=10; %for an 11 point window

%Perform Correlation

for k=2:389

      MIChinacorr=NaN(401,1);

      MIChinacorr(k,1)=
  [corr(MI18Ocorr(k:k+window_size,1),China18Ocorr(k:k+window_size,1))];
  end

Thanks for your help.

Answer 1

[Walter Roberson]

Every iteration of the "for k" loop, you are assigning

MIChinacorr=NaN(401,1);

so you are overwriting all of MiChinacorr with NaN.

You should only initialize it once, before the loop.

[Claire]

That's it! I knew I was doing something silly, I just couldn't see it.

Thanks so much for your help. Claire.

Answer 2

[Roger Stafford]

If you wrote the code just as you show it, you would need to add an ellipsis after the equal sign:

 MIChinacorr(k,1)= ...