I need to evaluate the following integral:
[tex]\int_0^{\pi} \lleft(\frac{P_n^1}{\sin\theta} \frac{d P_l^1}{d\theta}\right)\, \sin\theta\, d\theta [tex]
This integral, I think, has a closed form expression. Itarises in elastic wave scattrering. I am an engineer and do not have suficient...