complex output for real integral

*To*: mathgroup at smc.vnet.net*Subject*: [mg115843] complex output for real integral*From*: Ted Sariyski <tsariysk at craft-tech.com>*Date*: Sat, 22 Jan 2011 03:23:34 -0500 (EST)

Hi, I get complex answer for an integral from Exp[1/x^3]/x^3 over the real axes: In[]:=f[n_] = Assuming[ {Element[x, Reals], Element[n, Integers], n >= 1}, Integrate[E^(1/x^3)/x^3, {x, n, Infinity}] ] Out[]:= 1/6 (-1)^(1/3) (-3 Gamma[5/3] + 2 Gamma[2/3, -(1/n^3)]) The imaginary part of f[n] is everywhere ~10^-16 and I could ignore it but I guess there is a better approach. I'll appreciate any help. --Ted