write your own function myinvk(k) that computes the inverse of the calibration matrix without using the matlab function inv. in matlab

main.m
function ki = myinvk(k)
% Computes the inverse of a 3x3 calibration matrix k
% without using the built-in function inv()
    d = k(1,1)*(k(2,2)*k(3,3)-k(2,3)*k(3,2)) ...
      - k(1,2)*(k(2,1)*k(3,3)-k(2,3)*k(3,1)) ...
      + k(1,3)*(k(2,1)*k(3,2)-k(2,2)*k(3,1));
    ki = zeros(size(k));
    ki(1,1) = (k(2,2)*k(3,3)-k(2,3)*k(3,2))/d;
    ki(1,2) = (k(1,3)*k(3,2)-k(1,2)*k(3,3))/d;
    ki(1,3) = (k(1,2)*k(2,3)-k(1,3)*k(2,2))/d;
    ki(2,1) = (k(2,3)*k(3,1)-k(2,1)*k(3,3))/d;
    ki(2,2) = (k(1,1)*k(3,3)-k(1,3)*k(3,1))/d;
    ki(2,3) = (k(1,3)*k(2,1)-k(1,1)*k(2,3))/d;
    ki(3,1) = (k(2,1)*k(3,2)-k(2,2)*k(3,1))/d;
    ki(3,2) = (k(1,2)*k(3,1)-k(1,1)*k(3,2))/d;
    ki(3,3) = (k(1,1)*k(2,2)-k(1,2)*k(2,1))/d;
end
717 chars
18 lines

main.m
k = [1 2 3; 4 5 6; 7 8 9];
ki1 = myinvk(k);
ki2 = inv(k);
disp('Inverse of k (myinvk):');
disp(ki1);
disp('Inverse of k (inv):');
disp(ki2);
disp('Error:');
disp(norm(ki1-ki2));
178 chars
10 lines

main.m
Inverse of k (myinvk):
  -0.5000    1.0000   -0.5000
   1.0000   -2.0000    1.0000
  -0.5000    1.0000   -0.5000

Inverse of k (inv):
  -0.5000    1.0000   -0.5000
   1.0000   -2.0000    1.0000
  -0.5000    1.0000   -0.5000

Error:
   2.2204e-16
246 chars
13 lines