Template:Math/EQ PminusHalf01

	$P_{-\frac{1}{2}}(z)$	$=$	$\frac{2}{\pi }\left[\frac{2}{z+1}{]}^{1/2}K\right(\sqrt{\frac{z-1}{z+1}})$	for example …	$P_{-\frac{1}{2}}(\cosh \eta )$	$=$	$[\frac{\pi }{2}\cdot \cosh \frac{\eta }{2}{]}^{-1}K(\tanh \frac{\eta }{2})$
Abramowitz & Stegun (1995), p. 337, eq. (8.13.1)					Abramowitz & Stegun (1995), p. 337, eq. (8.13.2)