Why is the or statement making something true?

I currently have this code:

scores=[99,85,67;90,65,69;98,95,97;80,85,89;98,77,87];
Max_quiz_scores = max(scores)
Overall_max_score=max(Max_quiz_scores);
if Overall_max_score==scores(1,3)|scores(2,3)|scores(3,3)|scores(4,3)|scores(5,3)
    disp('3rd column has the highest score')
else
    disp('3rd column does not have the highest score')
end

However, whenever I run it, I know the max score is 99 in the first column, but it displays that the third column has the highest score. What am I doing wrong? Am I doing something wrong with the | as or?

Answer 1

[the cyclist]

You need

Overall_max_score==scores(1,3) | Overall_max_score==scores(2,3) <etc>

You could do this more concisely as

ismember(Overall_max_score,scores(:,3))

or skip defining Overall_max_score altogether with

ismember(max(scores(:)),scores(:,3))

or

max(scores(:))==max(scores(:,3))

Both of these latter methods use the fact that the syntax

scores(:)

is the matrix scores as a single column vector.

Answer 2

[HaMo]

This is what a conditional OR statement looks like

if a == x || b == x || c == x

Look up the difference between | and ||

You can also shorten it to this:

    [~, ind] = max(max(scores))

Answer 3

[dpb]

"Am I doing something wrong with the | as or?"

Yes you are...the above is the same as

if Overall_max_score==(scores(1,3)|scores(2,3)|scores(3,3)|scores(4,3)|scores(5,3))

and

scores(1,3)|scores(2,3)|scores(3,3)|scores(4,3)|scores(5,3)

will always be logical True as long as even one person in the third column did better than a flat zero on any quiz. | returns only the logical or which is either 0 (false) or ~0 (true).

To write as you did would mean doing the test on each and every element as

if Overall_max_score==scores(1,3)| Overall_max_score==scores(2,3)| ...
   Overall_max_score==scores(3,3)| Overall_max_score==scores(4,3)| ...
   Overall_max_score==scores(5,3)
  ...

It would be much simpler to use the optional second return for max something like

 [Overall_max_score,imax]==max(Max_quiz_scores);
 if imax==3
   ...

You could get the same result as

[Overall_max_score,imax]=max(scores);      % return array max, location in array
[rmax,cmax]=ind2sub(size(scores),imax);    % convert index to subscripts row, column
if cmax==3
  ...

altho one doesn't get the column max'es this way for free...