In the following link:
http://www.mathworks.com/access/helpdesk/help/toolbox/symbolic/ch16.html

I got the suggestions that
"Note    To substitute a matrix A into the symbolic expression f, use the
command polyvalm(sym2poly(f), A), which replaces all occurrences of x by A,
and replaces the constant term of f with the constant times an identity
matrix."

My question is: when the function f is NOT a polynormial, I will get the
following error message:

??? Error using ==> sym.sym2poly
Not a polynomial.


Can you plz give some suggestions to address this?Thank you very much.
-- 

Yan ZHANG
http://yanzhang.shorturl.com/

 In the following link:
 http://www.mathworks.com/access/helpdesk/help/toolbox/symbolic/ch16.html

 I got the suggestions that
 "Note    To substitute a matrix A into the symbolic expression f, use the
 command polyvalm(sym2poly(f), A), which replaces all occurrences of x by A,
 and replaces the constant term of f with the constant times an identity
 matrix."

 My question is: when the function f is NOT a polynormial, I will get the
 following error message:

 ??? Error using ==> sym.sym2poly
 Not a polynomial.

 Can you plz give some suggestions to address this?Thank you very much.
 --

 Yan ZHANG
 http://yanzhang.shorturl.com/