x(:,i) - inv(H(x(:, i)) .* J(x(:,i)))
however that will produce a 2x2 output which will cause an error when you index it into
H(x(:, i)) is a 2x2 matrix, J(x(:,i)) is a 1x2 matrix. If you multiply these matricies, you either need to transpose the J term or switch the two terms
H(x(:, i)) * J(x(:,i)).'
J(x(:,i)) * H(x(:, i))
but matrix inversion using inv() requires the use of a square matrix and neither of those fulfill that requirement.
So, you've got some thinking to do regarding what the output should be and how you'll store it.