How to perfom this fitting in matlab

How to code this in matlab for least square fitting

f(i,j)= ai^2  + bj^2  + cij  +  di  +  ej  + f ,

similar to this

% fitting a plane by least squares method
function rr = plane1(x,y,z)
  m1 = length(x);
  n1 = length(y);
  a11 = n1*x'*x;  a12 = sum(sum(x*y'));   a13 = n1*sum(x);
  a21 = a12;      a22 = m1*y'*y;          a23 = m1*sum(y);
  a31 = a13;      a32 = a23;              a33 = m1*n1;
  A = [a11 a12 a13;a21 a22 a23;a31 a32 a33];
  for i = 1:m1
    k1(i) = sum(x(i)*z(i,:));
  end
  b1 = sum(k1);
  for j =1:n1
    k2(j) = sum(y(j)*z(:,j));
  end
  b2 = sum(k2);
  b3 = sum(sum(z));
  B = [b1 b2 b3]';
  coff = A\B;
  a = coff(1);b = coff(2);c = coff(3);
  for i = 1:m1
    for j = 1:n1
      z0(i,j) = a*x(i)+b*y(j)+c;
    end
  end
  rr = z-z0;true
end