在运行条件极大似然估计是调用了fmincon这个函数，程序如下：
options=optimset('fmincon');
options=optimset(options,'display','off','hessupdate','bfgs','MaxIter',[80]);

A=[0 0 -1 -1 -1 0 0 -1 -1 -1 -1 0 0;0 0 0 0 0 -1 -1 1 1 1 1 0 0];
b=[0;1];
[x,fval,exitflag,output,grad,hessian]=fmincon(@ofn,x,A,b,[],[],[],[],[],options)
出现的错误提示是：
Warning: Matrix is singular to working precision.
(Type "warning off MATLAB:singularMatrix" to suppress this warning.)
> In E:\应用软件\matlab\work\ofn.m at line 1455
  In E:\应用软件\matlab\toolbox\optim\private\nlconst.m at line 264
  In E:\应用软件\matlab\toolbox\optim\fmincon.m at line 458
  In E:\应用软件\matlab\work\SWAECH.m at line 1412
这是怎么回事呀，各位高手，帮忙看看了，谢谢