急求助：最小二乘参数拟合遇到的问题

最小二乘参数拟合遇到的问题
用lsqlin命令进行参数拟合时总是给出如下提示，该怎么改进呢，请高人指点

Optimization terminated: relative function value changing by less
than sqrt(OPTIONS.TolFun), and rate of progress is slow.

resnorm =

  1.0465e+004

exitflag =

     3


output =

       iterations: 25
        algorithm: 'large-scale: trust-region reflective Newton'
    firstorderopt: 288.1820
     cgiterations: 409
          message: [1x123 char]