Associated Legendre functions and orthogonality

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SUMMARY

The discussion focuses on the orthogonality property of the associated Legendre functions, specifically the integral involving the functions P_l^{|m|}(cosθ) and P_{l'}^{|m'|}(cosθ). The integral is defined as ∫_{0}^{π}P_{l}^{|m|}(cosθ)·P_{l'}^{|m'|}(cosθ)sinθdθ=2(l+m)!/((2l+1)(l-m)!){δ}_{ll'}. The user seeks a similar orthogonality property for the derivative of the associated Legendre function, P^{'}_{l}^{|m|}(cosθ), and provides its derivative formula. They express a need for further insights into the orthogonality of the derivatives, as existing spherical harmonics literature has not yielded satisfactory results.

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  • Understanding of associated Legendre functions
  • Familiarity with spherical harmonics
  • Knowledge of integral calculus
  • Basic concepts of orthogonality in mathematical functions
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Mathematicians, physicists, and students studying spherical harmonics, particularly those interested in the properties of associated Legendre functions and their derivatives.

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According to the orthogonality property of the associated Legendre function

P_l^{|m|}(cos\theta)

we have that:

\int_{0}^{\pi}P_{l}^{|m|}(cos\theta){\cdot}P_{l'}^{|m'|}(cos\theta)sin{\theta}d\theta=\frac{2(l+m)!}{(2l+1)(l-m)!}{\delta}_{ll'}

What I am looking for is an orthogonality property for the derivative of the associated Legendre function

P^{'}_{l}^{|m|}(cos\theta):

something like that perhaps:

\int_{0}^{\pi}P^{'}_{l}^{|m|}(cos\theta){\cdot}P^{'}_{l'}^{|m'|}(cos\theta)sin{\theta}d\theta=?

or even taking into consideration the fact that the derivative of the associated Legendre function is:

P^{'}_{l}^{|m|}(cos\theta)=\frac{lcos{\theta}P_{l}^{|m|}(cos\theta)-(l+m)P_{l-1}^{|m|}(cos\theta)}{sin\theta}

after some manipulations on my equation an orthogonality property over the sum below:

\sum_{l}^{\infty}\sum_{m=-l}^{m=l}cos{\theta}P_{l}^{|m|}(cos\theta)-(l+m)P_{l-1}^{|m|}(cos\theta)e^{jm\phi}

Thanks in advance
 
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I am looking for a similar thing. I have looked in all the spherical harmonics textbooks I can find, but have had no luck. I will let you know if I have anything.
 

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