MATLAB: What does this section of code do

battleshipgame

I am creating a Battleship style game for a class project and I found this piece of code found below and my game only works with it in the code. I would like to have a better understanding of what the variables mean, they are not used in the code prior to this(other than "board"). Thank you for any help given.
i = 1+size*rand;
j = 1+size*rand;
loop = 1;
while (loop)
   temp = rand * 3;
   dx = 0;
   if (temp > 2)
      dx = 1;
   elseif (temp < 1)
      dx = -1;
   end
      temp = rand * 3;
   dy = 0;
   if (temp > 2)
      dy = 1;
   elseif (temp < 1)
      dy = -1;
   end
     i0 = dx * 4 + i;
     j0 = dy * 4 + j;
     if (i0 > 0 && i0 <= size && j0 > 0 && j0 <= size)
        loop = 0;
     end
     if (dx == 0 && dy == 0)
        loop = 1;
     end
  end   
for I = 0:3
   Board(int32(i + I * dx),int32(j + I * dy))=1;
end

Best Answer

It looks like:
i & j are generated as a random point on the board.
dx and dy are generated as a random direction (they are either -1, 0, or 1)
dx and dy are then checked to see that, when 4 is added to i and j in the dx and dy directions, the result is still on the board. If everything is still on the board, then the while loop exits. Otherwise, new random dx and dy directions are generated for testing. Also, at least one of dx or dy must be non-zero for the while loop to exit.
Then the board i and j position as well as three additional positions in the direction of dx and dy are assigned a value of 1.
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