MATLAB: While Loop problems

MATLABmatrix

I am trying to write a while loop. I want to read a matrix first, once ive done this i want to ask the user for co-ordinates, if those co-ordinates lie outside the matrix i want to display "these co-ordinates dont lie within the mining area" since the matrix displays a mine.
Once a suitable set of co-ordinates within the matrix is established i then want to ensure that the value in the matrix selected is zero, should the value not be zero i want to ask the user for a new set of co-ordinates.
Here's what i have so far,i feel like i lmost have it worked out however i just cant get the last part to work.
dirt_grid = csvread('dirtgrid.csv');
for base_station_x = input('Enter an x co-ordinate for the base station: ' );
    if base_station_x > length (dirt_grid)
       disp('The x co-ordinate is outside the mining area, please enter another co-ordinate')
        base_station_x = input('Enter an x co-ordinate for the base station: ' );
  end
end
for base_station_y = input('Enter an y co-ordinate for the base station: ' );
   while base_station_y > length (dirt_grid)
        disp('The y co-ordinate outside mining area, please enter another co-ordinate')
        base_station_y = input('Enter an y co-ordinate for the base station: ' );
    end
end
base_station = dirt_grid (base_station_x, base_station_y);
    while base_station >= 1
        disp('The location you have entered is not a valid location')
    end
I am aware that this program forms a infinite loop but im not sure where i should place this last loop to make the problem work. Thanks for any assistance anyone is able to provide…

Best Answer

This is one way to go about doing it. (x is from left to right, and y is from top to bottom.)
dirt_grid =[  0     1     1     0     1
              1     1     0     0     1
              1     1     1     0     0];
base_location_is_zero = false;
while ~base_location_is_zero
      try
          isok = 0;
          while ~isok
              base_station_x = input('Enter an x co-ordinate for the base station: ' );
              if ~ismember(base_station_x, 1:size(dirt_grid,2))
                  disp('The x co-ordinate is outside the mining area, please enter another co-ordinate')
              else
                  isok = 1;
              end
          end;
          isok = 0;
          while ~isok
              base_station_y = input('Enter an y co-ordinate for the base station: ' );
              if ~ismember(base_station_y, 1:size(dirt_grid,1))
                  disp('The y co-ordinate is outside the mining area, please enter another co-ordinate')
              else
                  isok = 1;
              end
          end;
          base_station = dirt_grid (base_station_y, base_station_x);
          if base_station ~= 0
              disp('The location you have entered is not a valid location')
          else
              base_location_is_zero = true;
          end
      catch
          disp('Bad input. Put in an integer and try again.')
      end
end;
disp('Everything is ok!');
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