What is $$\int_{\frac{\pi}{2}}^{\pi} P_l(\cos(\theta))P_{l'}(\cos(\theta)) \sin(\theta) d\theta$$ in general? Of course, $P_l$ is the l-th Legendre polynomial. Obvisiouly it is for even/even and odd/odd $$\frac{1}{2n+1} \delta_{nm}$$ and otherwise?
2026-04-11 23:53:16.1775951596
Integral with Legendre polynomials
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