% hold off
Epsilo = 0.005
MaxSteps = 200
step = 0.1;
v = 4
H = 0.0001;

% [x,y] = meshgrid(-v:step:v, -v:step:v);
[x,y] = meshgrid(-v:step:v, -v:step:v);

% func =  sym('x1^2 + y1^2')
func = sym('(1-x1)^2 + 100*(y1-x1^2)^2');
% func = sym('2*x1^2 + y1^2 + x1*y1')
% func = sym('-2*x1^2 - y1^2 + x1*y1')
syms x1 y1
% func = sym('sin(((1/2)*x1^2)-((1/4)*y1^2) + 3)*cos(2*x1 + 1 - exp(y1))');
func_hl = matlabFunction(func);

derivateX = diff(func, x1);
derivateX = matlabFunction(derivateX);

derivateY = diff(func, y1);
derivateY = matlabFunction(derivateY);

z = func_hl(x,y);

stX = -0.8;
stY = -1.5;
% stX = -2;
% stY = -0.25;

hold on;
contour(x,y,z, 32);
% surfc(x,y,z);
% clabel(C, h);    % Отображение меток  на линиях уровня
% quiver(x,y,gx,gy);


X = stX, Y=stY
steps = 0
plot(X,Y,'+');
% break

for i=1:MaxSteps
    derX = derivateX(X, Y);
    derY = derivateY(X, Y);

    derX = derX * H;
    derY = derY * H;


     X = X - derX;
     Y = Y - derY;

     plot(X,Y,'x');
     steps = steps + 1;
     if sqrt(derX^2 + derY^2) <= Epsilo;
         break
     end

end


plot(X,Y,'r*');
X
Y

% hold on
hold off;