Simpson's 1/3rd Rule (Simple)

disp("------------------------Simpson's 1/3rd Rule------------------------")

str = input('Give an equation in x: ','s')  ;
% a = input('Enter lowerbound value:');
% a
% b = input('Enter upperbound value:');
% b

% str = "exp(1)"
a=-1;
b=1;
a
b

h = (b-a)/2;
x1 = a + h;
h

% f = inline(str,'x') ;
% f = str2func(['@(x) ',str]);

fa = exp(a) ;
fb = exp(b) ;
fx = 4* exp(x1) ;
I = (h/3)*(fa+fb+fx);


disp(['Ans: ', num2str(I)])