www.gusucode.com > elmat工具箱matlab源码程序 > elmat/private/forsythe.m
function A = forsythe(n, alpha, lambda, classname) %FORSYTHE Forsythe matrix (perturbed Jordan block). % A = GALLERY('FORSYTHE',N,ALPHA,LAMBDA) is the N-by-N matrix % equal to the Jordan block with eigenvalue LAMBDA with the % exception that A(N,1) = ALPHA. % ALPHA defaults to SQRT(EPS) and LAMBDA to 0. % % The characteristic polynomial of A is given by % det(A-t*I) = (LAMBDA-t)^N - ALPHA*(-1)^N. % Copyright 1984-2005 The MathWorks, Inc. if isempty(alpha), alpha = sqrt(eps(classname)); end if isempty(lambda), lambda = zeros(classname); end A = jordbloc(n, lambda, classname); A(n,1) = alpha;