The Abel Poisson kernel \(\psi_{\kappa}\) on SO(3) is a nonnegative function depending on a parameter \(\kappa \in (0,1)\) and is defined by its Chebyshev series
\[ \psi_{\kappa}(t) = \sum\limits_{n=0}^{\infty} (2n+1) \, \kappa^{2n} \, \mathcal U_{2n}(t)\].
Syntax
psi = SO3AbelPoissonKernel(0.4)
psi = SO3AbelPoissonKernel('halfwidth',5*degree)