请教高手多元函数的条件极值问题，谢谢

minfly

下面一个多元函数的条件极值问题，范围限制不起作用，请高手指点，谢谢：）
>> fun='0.2647+2*0.1092*x(1)-2*0.2290*x(2)+0.7048*x(1)*x(1)-2*0.3810*x(1)*x(2)+0.4762*x(2)*x(2)';
>> x0=[0,0];
>> lb=[-0.5 0];
>> ub=[0.5 0.5];
>> [x,fval]=fmincon(fun,x0,lb,ub)
Warning: Large-scale (trust region) method does not currently solve this type of problem,
switching to medium-scale (line search).
> In C:\MATLAB6p5\toolbox\optim\fmincon.m at line 213
Optimization terminated successfully:
Magnitude of directional derivative in search direction
  less than 2*options.TolFun and maximum constraint violation
  is less than options.TolCon
No Active Constraints

x =

    0.1851    0.6290


fval =

0.        1409