MATLAB.rar_Numerical Recipes_making8qg_矩阵加速_艾特肯加速_艾特肯加速法

function [lambda,eigenvec,diff,ratio]=power_method(A,x_0,index,err_tol,max_iterates) n=size(A,1); x_init=zeros(n,1); lambda=zeros(max_iterates,1); for i=1:n x_init(i)=x_0(i); end [max_x,i_max]=max(abs(x_init)); z=x_init/x_init(i_max); if index==0 spec_vec=rand(1,n); end format long error=inf; it_count=0; while abs(error)>err_tol & it_count<max_iterates it_count=it_count+1; w=A*z; [max_w,i_max]=max(abs(w)); if index==0 lambda(it_count)=(spec_vec*w)/(spec_vec*z); else lambda(it_count)=w(index)/z(index); end if it_count>1 error=lambda(it_count)-lambda(it_count-1); end if it_count==max_iterates disp('your answers may possibly not satisfy your error tolerane') end end eigenvec=z; lambda=lambda(1:it_count); diff=zeros(it_count,1); ratio=zeros(it_count,1); diff(2:it_count)=lambda(2:it_count)-lambda(1:it_count-1); ratio(3:it_count)=diff(3:it_count)./diff(2:it_count-1);