How can I solve this problem in the matlab program ?

[Vuqar Samedov]

I use it in the matlab program, but the answer is not correct. I do not know why the answer is incorrect?

>> syms x

>> f=x*exp(-x^2);

>> u=(-2*x^2);

>> f=subs(f,u);

>> int(f)

ans =

-(x^3*(gamma(3/4) - igamma(3/4, 4*x^4)))/(2*(4*x^4)^(3/4))