view mftoolbox/logm_cond.m @ 8:a587712dcf5f draft default tip

funm_atom.m: rename fun_atom to funm_atom * funm_atom.m: rename fun_atom to funm_atom.
author Antonio Pino Robles <data.script93@gmail.com>
date Fri, 29 May 2015 09:48:36 +0200
parents 8f23314345f4
children
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function c = logm_cond(A)
%LOGM_COND  Relative condition number of matrix logarithm.
%   LOGM_COND(A) is the relative condition number in the Frobenius
%   norm of the matrix logarithm at the matrix A.

n = length(A);
N = n^2;
K = zeros(N);
E = zeros(n);

if ~isequal(A,triu(A))
   A = schur(A,'complex');
end

for j = 1:N
    e = zeros(N,1); e(j) = 1;
    E(:) = e;
    X = logm_frechet_pade(A,E);
    K(:,j) = X(:);
end

c = norm(K) * norm(A,'fro') / norm(logm(A),'fro');