gusucode.com > symbolic工具箱matlab源码程序 > symbolic/@single/charpoly.m
function P = charpoly(A,varargin) %CHARPOLY Characteristic polynomial of a matrix. % P = CHARPOLY(A) returns the coefficients of the characteristic % polynomial of the matrix A. If A is a SYM object, the vector returned % is a SYM object, too. Otherwise, a vector with doubles or singles % is returned, depending on the type of A. % % P = CHARPOLY(A,x) returns the characteristic polynomial of the matrix % A in terms of the variable x. Here x must be a free symbolic variable. % % Examples: % syms x; % A = sym([1 1 0; 0 1 0; 0 0 1]); % % P = charpoly(A) % returns [ 1, -3, 3, -1] % % P = sym2poly(charpoly(A,x)) % returns 1 -3 3 -1 % % P = charpoly(A,x) % returns x^3 - 3*x^2 + 3*x - 1 % % P = poly2sym(charpoly(A),x) % returns x^2 - 2*x + 1 % % See also MINPOLY, SYM/POLY2SYM, SYM/SYM2POLY, SYM/JORDAN, SYM/EIG, % SOLVE. % Copyright 2014 The MathWorks, Inc. oldDigits = digits(9); cleanupObj = onCleanup(@() digits(oldDigits)); P = charpoly(sym(A), varargin{:}); if nargin==1 P = single(P); end