请教关于最大似然估计求解问题

yubingp

clc;
clear;
clear all;
global x
b=3*exp(-3*x)./(1-exp(-3*x));
c=(158.*exp(-158*x))*25./(1-exp(-158*x));
A=[3,13,20,23,31,33,38,45,51,57,58,63,65,73,86,88,92,94,101,104,115,141,150,152,158];
for i=2:(length(A))
    b=b+(A(i)*exp(-A(i)*x)-A(i)*exp(-A(i)*x))./(exp(-A(i-1)*x)-exp(-A(i)*x));
end
x=solve('b=c','x')
程序有问题
结果显示：> In solve at 140
  In solvemx at 11
x =
[ empty sym ]

[ 本帖最后由 eight 于 2008-3-10 16:24 编辑 ]

ocean0107

定义sym

prince00840

b=b+(A(i)*exp(-A(i)*x)-A(i)*exp(-A(i)*x))./(exp(-A(i-1)*x)-exp(-A(i)*x));

这个分子错了:lol 成零了？是不是故意改错的？