How do I plot fractional orders of the Bessel function of the first kind (e.g. J_{1/3}(x))? Can I still use the besselj function?

clc;clear all;clf;

x=-20:0.1:20;

J1/3=besselj(1/3,x);

figure(1)

plot(x,J1/3,'k');

grid on

legend('J_{1/3}')

xlabel('x');ylabel('J_1/3(x)')