MATLAB: What is wrong with the code? Cycle while help

elseififmatrixwhile

Given a matrix called 'Heights' we should answer with a matrix called 'Path' that goes from space Heights(1,1) to space Height(m,n).
Matrix 'Heights'
   10 | 12 | 15 
  ---------------
   11 | 11 | 12
  ---------------
   13 | 14 | 15
So we are in Heights(1,1) and we can only move only – East – Southeast – South – (if the spaces have the same values we preferred first Southeast then East then South)
Matrix 'Path'
      1  1  10
      2  2  11
      2  3  12
      3  3  15
The code:
function Path = get_path(Heights)
        m = 1;
        n = 1;
        M = [1,1,Heights(1,1)];
          % Southwest = Heights(m+1,n+1)
          %      East = Heights(m,n+1)
          %     South = Heights(m+1,n)
          while m <= size(Heights,1) && n <= size(Heights,2)
              if m < size(Heights,1) && n < size(Heights,2)
                  if Heights(m+1,n+1) <= Heights(m,n+1) && Heights(m+1,n+1) <= Heights(m+1,n)
                      M = [M; m+1,n+1,Heights(m+1,n+1)];
                  elseif Heights(m+1,n+1) <= Heights(m,n+1) && Heights(m+1,n+1) > Heights(m+1,n)
                      M = [M; m+1,n,Heights(m+1,n)];
                  elseif Heights(m+1,n+1) > Heights(m,n+1) && Heights(m,n+1) <= Heights(m+1,n)
                      M = [M; m,n+1,Heights(m,n+1)];
                  elseif Heights(m+1,n+1) > Heights(m,n+1) && Heights(m,n+1) > Heights(m+1,n)
                      M = [M; m+1,n,Heights(m+1,n)];
                  end
              elseif m == size(Heights,1) && n < size(Heights,2)
                  M = [M; m,n+1,Altitudes(m,n+1)];
              elseif m < size(Heights,1) && n == size(Heights,2)
                  M = [M; m+1,n,Heights(m+1,n)];
              elseif m == size(Heights,1) && n == size(Heights,2)
                  M = [M; m,n,Heights(m,n)];
              end
          end
          Caminho = M
end
The problem is when I go to the command line and call the function is just stays blank…

Best Answer

You need to break out of the loop when you hit the bottom corner. Also, you need to add in code that updates m and/or n as you build the path. E.g.,
              elseif m < size(Heights,1) && n == size(Heights,2)
                  M = [M; m+1,n,Heights(m+1,n)];
                  m = m + 1;  % <-- add code like this to other branches also
 %              elseif m == size(Heights,1) && n == size(Heights,2)  <-- don't need this
 %                  M = [M; m,n,Heights(m,n)];
              end
              if m == size(Heights,1) && n == size(Heights,2)
                  break;
              end
Your current code is an infinite loop. Stepping through the code with the debugger and examining m, n, and M as you go would have shown you this.
What is "Altitudes"? Is that a typo?
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