Vectorize nested for loops

Hi, I would like to vectorize the following loop, have tried generating indices and but so far been successful.

a = any 1D vector
N = some value
for i=1:length(a)
      for j=(i+1):length(a)
          if(a(i)-a(j) > N)
             disp('Far');
          end
      end    
end

Does anyone have any ideas on this ?

[Guillaume]

The ability of vectorising loops depends solely on the do something. So if you don't tell us what it is, we can't answer your question.

[Balkrishna Patankar]

Updated

Answer 1

[Guillaume]

Your example is trivially vectorised:

%R2016b or later:
isgreater = (a - a.') > N;

%any version:
isgreater = bsxfun(@minus, a, a.') > N;

isgreater(r, c) is true (1) when a(r)-a(c) > N

[Balkrishna Patankar]

This is not giving the correct answer. For example, if I run the following program :

N=-2;
b=[1 1 1;2 2 2;3 3 3;4 4 4;5 5 5];
a=[1;2;3;4;5];

   for i = 1:length(a)
       for j = (i+1):length(a)
           if(a(i)-a(j) > N)
               disp('Far');
           end
       end
   end

This displays Far 4 times which means there ought to be 4 1's in your matrix.

isgreater = (a - a.') > N;

Gives 19 ones.

[Guillaume]

Indeed, my answer was equivalent to having the j loop starting at 1 instead of i+1. The upper triangle of that isgreater matrix is the exact equivalent of your loops, so:

isgreater = triu((a - a.') > N, 1)

[Balkrishna Patankar]

Thanks this worked !