exa3_16.m

有关matlab r2007的实用教程

f=sym('a*x^2+b*x+c')    % create a function f(x)

subs(f,'s','x')    % substitute ‘s’ for ‘x’ in the expression f 

subs(f,'alpha','a')    % substitute ‘alpha’ for ‘a’ in  f 

g=sym('3*x^2+5*x-4')   % create another function

h=subs(g,'x','2')    % substitute '2’for ‘x’ in  g 

isstr(h)   % show that the result is a symbolic expression