Function Output Not Displaying

 function output = IsMagic(n)
  A= zeros(n);
  r=n;
  c=n;
  row_index = 1;
  while row_index <= r
      col_index=1;
      while col_index <= c
          A(row_index,col_index) = randi(1*n.^2);
          col_index=col_index + 1;

      end
      row_index= row_index +1;

end

      matrix=A;
      columnsum=sum(matrix);
      disp ('The sum for the columns is:')
      fprintf ('%d,\n', columnsum)
      rowsum=sum(matrix,2);
      disp ('The sum for the rows isL')
      fprintf ('%d,\n', rowsum)
      d1=sum(diag(matrix));
      d2=sum (diag(flip(A)));
      disp ('The sum for the diagonals is')
      fprintf ('%d, %d \n',d1,d2)
      if numel(unique(columnsum))==1
          if numel(unique(rowsum))==1
              if numel(unique(d1))==1
                  if numel (unique(d2))==1
                      if (columnsum(1)==(rowsum(1))&& (columnsum(1))== (d1(1)) && (columnsum(1))==(d2(1)))
                          output=1;
                      else
                          output=0;

                      end
                  end
              end
          end
      end

    end

The purpose of this code is to create a function called isMagic. The function takes one input n, creates a square matrix of size n × n using random integers between 1 and n2,and returns the logical value true (1) if the resulting matrix is a magic square and false(0) if it not a magic square.

I have done everything, but for some reason the output is not displaying. What am I doing wrong?

Answer 1

[Walter Roberson]

You do not assign output in some cases. You have a series of

if this
  if that
    if theother
       output=1
    else
       output=0;
    end
  end
end

Consider what would happen if "this" is not true: it would never get to try "that" and "the other" to assign to output.

One way of handling this is to assign 0 to output before the "if" structure and then only assign 1 in the case you can prove that it is "perfect". In all the other cases output would stay 0 which is what you want.

But you should also look at the "&" and "&&" operators

if this & that & theother