how to correct this for loop code?

for i=1:1:51
           for j=1:1:51
               if(i+1)>51
                   k=1;
               else
                   k=i+1;
               end
               a1h(i,j)=A1(i,j)-A1(k,j);
           end
       end
       %calculate vertical array
%        a=input('enter the matrix');
       for j=1:1:56
           for i=1:1:56
               if(j+1)>56
                   k=1;
               else
                   k=j+1;
               end
              a1v(i,j)=A1(i,j)-A1(i,k);
           end
       end

when i run this code getting this error...

??? Attempted to access A1(52,1); index out of bounds because size(A1)=[51,56].

Error in ==> matrixupdate at 182
              a1v(i,j)=A1(i,j)-A1(i,k);

Answer 1

[Walter Roberson]

In your first loop, you limit "i" and "j" to 51, but in the second loop you limit them to 56. If you want to work on a 51 x 56 array, limit i to 51 and limit j to 56.