Question

Matlab中fmincon函数使用出错

我自己写的如下：
function f=myfun(x);
f=-25.896-1.815*x(1)+0.765*x(2)-0.936*x(1)*x(2)+
0.707*x(1)^2+0.685*x(2)^2;
存为m文件，命名为fmin.m
然后在工作窗口运行
x0=[0;0];
[x,fval]=fmincon('fmin',x0,[],[],[],[],-1.68,1.68)
虽然出来了x =1.6686
0.5816
fval = -27.1878
但是还是有Warning: Large-scale (trust region) method does not currently solve this type of problem,
using medium-scale (line search) instead.
> In fmincon at 317
Optimization terminated: magnitude of directional derivative in search
direction less than 2*options.TolFun and maximum constraint violation
is less than options.TolCon.
No active inequalities.

请问我算出来的那个x,fval是正确的结果吗？
那个warning又是什么意思？是说让我换种搜索方法吗？

Answer 1

>> [x,fval]=fmincon('fmin',x0,[],[],[],[],-1.68,1.68)
Optimization terminated: magnitude of directional derivative in search
direction less than 2*options.TolFun and maximum constraint violation
is less than options.TolCon.
No active inequalities.

x =

1.668593592364594 0.581614920319626

fval =

-27.187778596177679

结果正确着呢！
因为你这是非线性有约束的最优化问题，只能用这个函数了

Answer 2

你那个m文件的函数名与文件名不一致，而且fmin是系统函数，应该换成其他与系统不重复的函数名