nlinfit函数问题，求各位帮帮忙

seaying

x=[0.25 0.5 0.75 1 1.5 2 2.5 3 3.5 4 4.5 5 6 7 8 9 10 11 12 13 14 15 16];
>> y=[30 68 75 82 82 77 68 68 58 51 50 41 38 35 28 25 18 15 12 10 7 7 4];
>> myfunc=inline('(beta(2)*beta(3)*(exp(-beta(1)*x)-exp(-beta(2)*x)))/(beta(2)-beta(1))','beta','x');
>> beta=nlinfit(x,y,myfunc,[0.5 0.5 0.5]);
Warning: Divide by zero.
> In inlineeval at 13
  In inline.subsref at 25
  In nlinfit at 74
Warning: Divide by zero.
> In inlineeval at 13
  In inline.subsref at 25
  In nlinfit at 152
Warning: Matrix is singular to working precision.
> In nlinfit at 161

>> k1=beta(1),k2=beta(2),k3=beta(3);

k1 =

   NaN


k2 =

   NaN

>> 为什么会出现警告呢？而且还没有数值结果，求指教

seaying

在线等结果

seaying

感觉是myfunc=inline('(beta(2)*beta(3)*(exp(-beta(1)*x)-exp(-beta(2)*x)))/(beta(2)-beta(1))','beta','x');
出问题的

madio

提示的是出现除数为零的问题了！