% Set up the expression of function "y"
% syms: creating symbolic variables and functions
syms x
y = 5.0 * cos(2.0 *x) - 2.0 * x* sin(2.0 * x);

% plot the graph of the function "y" 
ezplot(y,[0.5,2]);

g=diff(y,x)  % compute the derivative of "y"

 % compute the zeros of the equation g = 0; "g" is the 
 % derivative of "f". The soln is saved in root_g;
 root_g = fzero(char(g),[1, 2])                              
 
% evaluate the value of "y" at the  point where x = root_g 
% subs(): Substitute parameter x with a floating-point number. 
%vpa(): Approximate the result of substitution returned by
%       subs() with floating-point values
out = vpa(subs(y,x, root_g))        

left = vpa(subs(y,x,1))
right = vpa(subs(y,x,2))

%f = cos(x);
%Tay3 = taylor(f,4)