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7.5 特征值问题的若干 Matlab 函数文件

7.5 特征值问题的若干 Matlab 函数文件. 7.5.1 幂法的 Matlab 函数文件. 7.5.2 反幂法的 Matlab 函数文件. 7 .5.3 QR 算法的 Matlab 函数文件. 7.5.1 幂法的 Matlab 函数文件 function[z,m]=power_m(A,max_it,tol) [n,nn]=size(A);z=ones(n,1); it=0;error=100;

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7.5 特征值问题的若干 Matlab 函数文件

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  1. 7.5 特征值问题的若干Matlab函数文件 7.5.1 幂法的Matlab函数文件 7.5.2 反幂法的Matlab函数文件 7.5.3 QR算法的Matlab函数文件

  2. 7.5.1 幂法的Matlab函数文件 function[z,m]=power_m(A,max_it,tol) [n,nn]=size(A);z=ones(n,1); it=0;error=100; disp(‘it m z(1) z(3) z(4) z(5)’)%该文件用于不超过5阶的矩阵。 while it <max_it&error>tol w=A*z;ww=abs(w); [k,kk]=max(ww);%kk为ww最大元素的标号。 m=w(kk); %特征值的近似值。 z=w/w(kk); %特征向量的近似值。 out=[it+1 m ];disp(out)

  3. 7.5.2 反幂法的Matlab函数文件 function[z,m]=invpower(A,max_it,tol) [n,nn]=size(A);z=ones(n,1);it=0;error=100; [L,U]=lu_factor(A); while it<max_it&error>tal w=lu_solve(L,U,z);ww=abs(w);[k,kk]=max(ww); m=( *z)/( *w);z=w/w(kk); out=[it+1 m ];disp(out) error=norm(A*z-m*z); it=it+1; end Error=norm(A*z-m*z); it=it+1; End error

  4. 7.5.3 QR算法的Matlab函数文件 function[Q,R]=qr_factor(A) % 矩阵A的QR分解。 [n,nn]=size(A);R=A;Q=eye(n); for k=1:n-1 x=zeros(n,1);x(k:n,1)=R(k:n,k); g=norm(x);v=x;v(k)=x(k)+g; s=norm(v);w=v/s;u=2* *w; R=R-w* ;Q=Q-2*Q*w* ; end function e=qr_eig(A,max) % 用QR算法求矩阵A的特征值。 for i=1:max [Q,R]=qr_factor(A); A=R*Q; end e=diag(A)

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