# Evaluate a certain integral

I am a beginner with Mathematica, and I would like to know if it is possible to calculate this kind of integral:

$$\int\limits_0^{0.8}\cos^2 \left(\frac{\pi z}{1.6} \right)\int\limits_z^{\infty}\frac{e^{-3.367u}}{u^2}du\ dz$$

• I see two integrals signs, but only one d something at the end. Is this mathematically even valid? – Nasser Dec 21 '17 at 14:45
• already corrected, thanks! – Rafael Dec 21 '17 at 14:48
• Did you check the documentation for Integrate or NIntegrate yet? – march Dec 21 '17 at 21:03

 int1=Assuming[z>= 0,Integrate[  Exp[-3367/1000 u]/u^2,{u,z,Infinity}]]

You see that it has to be for z>0 now evaluate the complete integral
 Integrate[ Cos[ Pi z/(16/10)]^2* int1 ,{z,0,8/10},PrincipalValue->True]