Please Help - Explicit integral could not be found

t au=(0.2e-9); %fixed value of tau.

syms t; % t is the continous variable i.e TIME

s=(1-4*pi*((t/tau)^2))*exp(-2*pi*((t/tau)^2)); %continous signal, whose normalised autocorrelation is to be found

Eg=int(s^2,t,-inf,inf); % I am getting ENERGY = 7.5e-011   

% AUTOCORRELATION HERE "w" is the lag,whose value would be=1e-9 or integer multiple of 1e-9.

% I am calculating in this way

s2=subs(s,t,t+w); % subs is used for substituting t with t+w.

acf=int(s*s2,t,-inf,inf);

%getting error- "Explicit integral could not be found "

Answer 1

[Christopher Creutzig]

syms w positive
acf = simplify(acf);
ws = 0:1e-9:1e-7;
plot(ws, double(subs(acf, w, ws)));

or, probably better, since the numbers get far too small for double very quickly,

plot(ws, double(log10(subs(acf, w, sym(ws)))))