斐惹尔斯函数(Ferrers Functions)是连带勒让德方程的实数解,分为第一类斐惹尔斯函数和第二类斐惹尔斯函数。分别定义如下[1]
P v μ ( x ) = ( 1 + x 1 − x ) μ / 2 ∗ F ( v + 1 , − v ; 1 − μ ; 1 / 2 − x / 2 ) Γ ( 1 − μ ) {\displaystyle P_{v}^{\mu }(x)=({\frac {1+x}{1-x}})^{\mu /2}*{\frac {F(v+1,-v;1-\mu ;1/2-x/2)}{\Gamma (1-\mu )}}}
Q v μ ( x ) = ( c o s ( μ ∗ π ) ∗ ( 1 + x 1 − x ) μ / 2 ) F ( v + 1 , − v ; 1 − μ ; 1 / 2 − 2 / x ) Γ ( 1 − μ {\displaystyle Q_{v}^{\mu }(x)=(cos(\mu *\pi )*({\frac {1+x}{1-x}})^{\mu /2}{\frac {)F(v+1,-v;1-\mu ;1/2-2/x)}{\Gamma (1-\mu }}}
P v μ ( x ) = ( − 1 + x − 1 + x ) 1 / 2 μ H e u n C ( 0 , − μ , 2 v + 1 , 0 , v + 1 / 2 + v 2 , − 1 + x 1 + x ) ( ( 1 / 2 + 1 / 2 x ) v + 1 ) − 1 ( Γ ( 1 − μ ) ) − 1 {\displaystyle P_{v}^{\mu }(x)=\left(-{\frac {1+x}{-1+x}}\right)^{1/2\,\mu }{\it {HeunC}}\left(0,-\mu ,2\,v+1,0,v+1/2+{v}^{2},{\frac {-1+x}{1+x}}\right)\left(\left(1/2+1/2\,x\right)^{v+1}\right)^{-1}\left(\Gamma \left(1-\mu \right)\right)^{-1}}