matlab:追赶法（crout分解）工具箱

function x=chase (a,b,c,f) 
% the method of chaase*******************************
%  a, b, c,分别是是方程组的下对角，主对角，上对角的三条
%  alpha，beta， gama分别是Crout分解的主和次对角线
%    /beta(1)    0    ...             ...        0  0     \
%    |alpha(2)   beta(2)  ...          ...       0  0     | 
%  L=|0          alpha(3) ...beta(3)                      |
%    |                                                    |
%    |                                                    |
%    \                                   alpha(3) beta(n) /
%********************************************************
beta(1)=b(1);gama(1)=c(1)/beta(1);y(1)=f(1)/beta(1);
for i=2:length(b)
alpha(i-1)=a(i-1);beta(i)=b(i)-alpha(i-1)*gama(i-1);
if i<=length(b)-1
    gama(i)=c(i)/beta(i);
end
y(i)=(f(i)-alpha(i-1)*y(i-1))/beta(i);
end
x(length(b))=y(length(b));
for i=length(b)-1:-1:1
x(i)=y(i)-gama(i)*x(i+1);
end