matlab 中极大似然法mle错误求助

kinde67

clc;clear;
A=csvread('c:\wk.txt');
m=6;
n=floor(length(A)/m);
for i=1:n;
    y(i)=max(A([(i-1)*m+1:(i*m)]));
end
%hist(y,15);
x=y;
mypdf=@(x,a,b,u)(exp(-(1+b.*(x-u)/a).^(-1/b))./b.*(-(1+b.*(x-u)/a).^(-1/b-1)));
mycdf=@(x,a,b,u)(exp(-(1+b.*(x-u)/a).^(-1/b)));
[paramhat,paramint]=mle(x,'pdf',mypdf,'cdf',mycdf,'start',[.1,.5,.1])


Error using mlecustom>llf_pdfcdf (line 440)
The PDF function returned negative or zero values.

Error in fminsearch (line 191)
fv(:,1) = funfcn(x,varargin{:});

Error in mlecustom (line 183)
        [phat,nll,err,output] = ...

Error in mle (line 229)
            [phat, pci] = mlecustom(data,varargin{:});

Error in Untitled2 (line 12)
[paramhat,paramint]=mle(x,'pdf',mypdf,'cdf',mycdf,'start',[.1,.5,.1])

madio

这个和你的概率密度函数的定义有关，错误提示说这个函数返回了负值或者零值，这是不允许的，你好好推敲一下它的定义
Error using mlecustom>llf_pdfcdf (line 440)
The PDF function returned negative or zero values.

kinde67

表情那里是    冒号和（