Unable to convert expression into double array.

[FANG LIU]

how to handle this question.

Answer 1

[Star Strider]

One way is to integrate it numerically rather than symbolically:

syms w 
fun1pdf(w) = exp(w)/((1+exp(w))^2);
fun1mu(w) = w^3*fun1pdf(w);
F1mu = vpa(int(fun1mu,-Inf,Inf))

fun1mufcn = matlabFunction(fun1mu);
F1mu = integral(fun1mufcn, -Inf, Inf)

However, the result is:

F1mu =
   NaN

[FANG LIU]

Yes, It is strange, when I try w^2*fun1pdf(w), and w^4*fun1pdf(w), it works.

only for w^3, it is bad.

[Star Strider]

I discovered the same problem. That is the reason I went to the integral function. It does produce a result, even though it may not be the one you may want.

[FANG LIU]

anyhow, Thanks.