syms x


hold on
fplot(erf(x/sqrt(4)),[-5 5])
fplot(erf(x/sqrt(4*4)),[-5 5])
fplot(erf(x/sqrt(4*16)),[-5 5])
fplot(erf(x/sqrt(4*64)),[-5 5])
grid on
legend('t=1', 't=4', 't=16', 't=64', 'Location', 'northwest')
xlabel('x')
ylabel('C(x)')
hold off