Variable is changed but the value seems to be unused

% code
function output = crosscorr1(y1,y2)
    xcf = crosscorr(y1, y2); 
    [xcf,lags,bounds] = crosscorr(y1,y2);
    if xcf(:,:) >= bounds(1,1)
        xcf(:,:) <= bounds(1,2)
        Significance(1).Sig = 'yes'
    else
        Significance(1).Sig = 'no'
    end  
end

I want to state in the Significance array, row 1, column Sig 'yes' or 'no' depending on the if/else statement. I keep receiving a message that the variable (Significance) is not used. When I check this variable, it is indeed not used even though the if/else statement appears to be working. How can I get this to work? Thank you for your help in advance.

Answer 1

[the cyclist]

I assume that xcf is not a scalar. If that is the case, then in the statement

if xcf(:,:) >= bounds(1,1)

all of the elements of xcf have to satisfy the condition, to enter into that control structure. In other words, the if is not parallelized.

[HABmatlab]

Hi, Thank you for your response.

Xcf is not scalar (it is a 41 X 1 double), it refers to table with one column of numbers. The if statement works if I replace:

    % code
  Significance(1).Sig = 'yes'
    else
        Significance(1).Sig = 'no'

with

    % code
  Disp('yes')
else
Disp('no')

The if/else statement also works when I put it in a script, it just does not work when it is in a function file. Do you think it may have something to do with the function file? Or do I need to make xcf scalar somehow to do this?

[the cyclist]

Can you give an example of inputs y1, y2 that exhibits the behavior you are describing?

Answer 2

[Walter Roberson]

Note that your code

    if xcf(:,:) >= bounds(1,1)
        xcf(:,:) <= bounds(1,2)

is equivalent to

    if all(xcf >= bounds(1,1))
       disp( reshape(xcf <= bounds(1,2), size(xcf, 1), []) )

Is that what you want? Or do you want something like

    if all( xcf(:) >= bounds(1,1) & xcf(:) <= bounds(1,2) )

[HABmatlab]

Hi Walter, thank you for your response.

I actually want if ANY value in xcf is larger than bounds(1,1) or smaller than bounds (1,2) for a "yes" to be put into array Significance(1).Sig. I was able to get the following code to work:

 %
if any(xcf >= bounds(1,1));
    any(xcf <= bounds(1,2)); 
    disp('yes')
else
    disp('no')
end

So I can display a "yes" or "no" but I can't get it to go into the array.

[Walter Roberson]

      if any( xcf(:) >= bounds(1,1) ) || any(xcf(:) <= bounds(1,2))
        Significance(1).Sig = 'yes';
      else
        Significance(1).Sig = 'no';
      end

... But your function returns output which you never assign a value to, and does not return Significance