am trying to write a matlab program to solve dogleg method for trust region problem, but the program is not working properly. Below is the program. Please i really need your help and suggestions. Thanks

clear all
fprintf('       k       f0       X(1,1)    X(2,1)       r         b\n')
syms x1 x2
X = [x1 ; x2];
f = (x2 - 0.129*x1^2 + 1.6*x1 - 6)^2 + 6.07*cos(x1) + 10;
w = jacobian(f,X);
g1 = w';
h1 = jacobian(jacobian(f,X));
k = 0;
datasave = [];
x1 = 6; x2 = 14;  
g = eval(g1);
h = eval(h1);
b = norm(g); %where b is tol
while k<15
    if (eig(h))>0
            H = h;
        else
            lambda = 0.01;
            V=abs(min(eig(h)));
            H = h + (V+lambda)*eye(size(h));
    end
    Y = inv(H);
    r = (g'*g)/(g'*H*g);
    pU = -r*g;
    pB = -Y*g;
    if 0<=r<=1
        P = r*pU;
    elseif 1<=r<=2
        P = pU + (r-1)*(pB-pU);
    end
    PP = norm(P);

      f = @(x1,x2) (x2-0.129*x1^2+1.6*x1-6)^2+6.07*cos(x1)+10; f0 = f(x1,x2);
      X = [x1;x2];
      W = g'*P;
      Z = 0.5*(P'*H*P);
      y = f0+W+Z;
      v = f0;
      A = X+P;
      x1 = A(1,1);
      x2 = A(2,1);
      q = f(x1,x2);
      Q = 0.2; R = 0.25; S = 0.75; I = 2.0; M = 5.0; B = 0.25; C = 2.0;
      e = (f0 - q)/(v - y);
      if e<R
          Inew = B*I;
      elseif e>S && PP==I
              Inew = min(C*I,M);
      else
          Inew = I;   
      end
      if e>Q
          Xnew = A;
      else
          Xnew = X;
      end
      datasave=[datasave; k f0 X(1,1) X(2,1) r b];
      Xnew = subs(Xnew);
      k = k+1;
      X = Xnew;
      x1 = X(1,1);
      x2 = X(2,1);
      gnew = eval(g1);
      b = norm(gnew);
      hnew = eval(h1);
      I = Inew; g = gnew;h=hnew; 

end
disp(datasave)