\[\left.\frac{\mathrm{d}\mathsf{P}^{\mu}_{\nu}\left(x\right)}{\mathrm{d}x}\right%
|_{x=0}=-\frac{2^{\mu+1}\pi^{1/2}}{\Gamma\left(\frac{1}{2}\nu-\frac{1}{2}\mu+%
\frac{1}{2}\right)\Gamma\left(-\frac{1}{2}\nu-\frac{1}{2}\mu\right)},\]