The integral function is going to produce one point — the value of the entire integral. If you want to plot it, use cumtrapz:
a = 2; % Input Value
b = 3; % Input Value
fun = @(x) x.^2; % Create Function To Test Code
x = linspace(a, b);
q = cumtrapz(x,fun(x));
fprintf('\n f = %6.4f\n',q(end)-q(1))
figure(1)
plot(x, q)
grid
