Integration of product of Associated Legendre Polynomial












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I am interested in the following integral $$I=int_{-1}^{1} P_s^t(x)P_u^v(x)mathrm{d}x~.$$ Does any one know if a closed form exist for a general $s, t, u, v$, and for $tneq v$ and $sneq u$?










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  • $begingroup$
    Legendre and Related Functions .
    $endgroup$
    – Felix Marin
    Sep 17 '16 at 2:34
















2












$begingroup$


I am interested in the following integral $$I=int_{-1}^{1} P_s^t(x)P_u^v(x)mathrm{d}x~.$$ Does any one know if a closed form exist for a general $s, t, u, v$, and for $tneq v$ and $sneq u$?










share|cite|improve this question









$endgroup$












  • $begingroup$
    Legendre and Related Functions .
    $endgroup$
    – Felix Marin
    Sep 17 '16 at 2:34














2












2








2





$begingroup$


I am interested in the following integral $$I=int_{-1}^{1} P_s^t(x)P_u^v(x)mathrm{d}x~.$$ Does any one know if a closed form exist for a general $s, t, u, v$, and for $tneq v$ and $sneq u$?










share|cite|improve this question









$endgroup$




I am interested in the following integral $$I=int_{-1}^{1} P_s^t(x)P_u^v(x)mathrm{d}x~.$$ Does any one know if a closed form exist for a general $s, t, u, v$, and for $tneq v$ and $sneq u$?







integration definite-integrals legendre-polynomials






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asked Sep 16 '16 at 23:08









titaniumtitanium

320111




320111












  • $begingroup$
    Legendre and Related Functions .
    $endgroup$
    – Felix Marin
    Sep 17 '16 at 2:34


















  • $begingroup$
    Legendre and Related Functions .
    $endgroup$
    – Felix Marin
    Sep 17 '16 at 2:34
















$begingroup$
Legendre and Related Functions .
$endgroup$
– Felix Marin
Sep 17 '16 at 2:34




$begingroup$
Legendre and Related Functions .
$endgroup$
– Felix Marin
Sep 17 '16 at 2:34










1 Answer
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I think your answer is in the paper, "The overlap integral of three associated Legendre polynomials" by Shi-Hai Dong and R. Lemus (2002) (https://www.sciencedirect.com/science/article/pii/S0893965902800040). The relevant expression is $I(s,t;u,v)$, given by equations (7-10), and yields



$$
int_{-1}^1 P^t_s(x) P^v_u(x)dx=(-1)^delta|v-t|2^{|v-t|-2}sqrt{frac{(s+t)!(u+v)!}{(s-t)!(u-v)!}}timessum_alpha (2alpha+1)left(1+(-1)^{alpha+|v-t|}right)sqrt{frac{(alpha-|v-t|)!}{(alpha+|v-t|)!}}frac{Gammaleft(frac{alpha}{2}right)Gammaleft(frac{alpha+|v-t|+1}{2}right)}{left(frac{alpha-|v-t|}{2}right)!Gammaleft(frac{alpha+3}{2}right)},
$$



with the phase



$$
delta=left{begin{matrix} m_1 & mbox{ if } & m_2geq m_1, \ m_2 & mbox{ if } & m_2<m_1,end{matrix}right.
$$



and this integral will only be non-zero if
$$
(|s-u|leqalphaleq s+u)wedge(alphageq|v-t|)wedge(alpha + s + umbox{ is even}).
$$



Note that there is nothing specifying that $tneq v$ or $sneq u$, so this formula may simplify a little under those assumption, I haven't checked.






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    1 Answer
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    1 Answer
    1






    active

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    active

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    active

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    0












    $begingroup$

    I think your answer is in the paper, "The overlap integral of three associated Legendre polynomials" by Shi-Hai Dong and R. Lemus (2002) (https://www.sciencedirect.com/science/article/pii/S0893965902800040). The relevant expression is $I(s,t;u,v)$, given by equations (7-10), and yields



    $$
    int_{-1}^1 P^t_s(x) P^v_u(x)dx=(-1)^delta|v-t|2^{|v-t|-2}sqrt{frac{(s+t)!(u+v)!}{(s-t)!(u-v)!}}timessum_alpha (2alpha+1)left(1+(-1)^{alpha+|v-t|}right)sqrt{frac{(alpha-|v-t|)!}{(alpha+|v-t|)!}}frac{Gammaleft(frac{alpha}{2}right)Gammaleft(frac{alpha+|v-t|+1}{2}right)}{left(frac{alpha-|v-t|}{2}right)!Gammaleft(frac{alpha+3}{2}right)},
    $$



    with the phase



    $$
    delta=left{begin{matrix} m_1 & mbox{ if } & m_2geq m_1, \ m_2 & mbox{ if } & m_2<m_1,end{matrix}right.
    $$



    and this integral will only be non-zero if
    $$
    (|s-u|leqalphaleq s+u)wedge(alphageq|v-t|)wedge(alpha + s + umbox{ is even}).
    $$



    Note that there is nothing specifying that $tneq v$ or $sneq u$, so this formula may simplify a little under those assumption, I haven't checked.






    share|cite|improve this answer









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      0












      $begingroup$

      I think your answer is in the paper, "The overlap integral of three associated Legendre polynomials" by Shi-Hai Dong and R. Lemus (2002) (https://www.sciencedirect.com/science/article/pii/S0893965902800040). The relevant expression is $I(s,t;u,v)$, given by equations (7-10), and yields



      $$
      int_{-1}^1 P^t_s(x) P^v_u(x)dx=(-1)^delta|v-t|2^{|v-t|-2}sqrt{frac{(s+t)!(u+v)!}{(s-t)!(u-v)!}}timessum_alpha (2alpha+1)left(1+(-1)^{alpha+|v-t|}right)sqrt{frac{(alpha-|v-t|)!}{(alpha+|v-t|)!}}frac{Gammaleft(frac{alpha}{2}right)Gammaleft(frac{alpha+|v-t|+1}{2}right)}{left(frac{alpha-|v-t|}{2}right)!Gammaleft(frac{alpha+3}{2}right)},
      $$



      with the phase



      $$
      delta=left{begin{matrix} m_1 & mbox{ if } & m_2geq m_1, \ m_2 & mbox{ if } & m_2<m_1,end{matrix}right.
      $$



      and this integral will only be non-zero if
      $$
      (|s-u|leqalphaleq s+u)wedge(alphageq|v-t|)wedge(alpha + s + umbox{ is even}).
      $$



      Note that there is nothing specifying that $tneq v$ or $sneq u$, so this formula may simplify a little under those assumption, I haven't checked.






      share|cite|improve this answer









      $endgroup$
















        0












        0








        0





        $begingroup$

        I think your answer is in the paper, "The overlap integral of three associated Legendre polynomials" by Shi-Hai Dong and R. Lemus (2002) (https://www.sciencedirect.com/science/article/pii/S0893965902800040). The relevant expression is $I(s,t;u,v)$, given by equations (7-10), and yields



        $$
        int_{-1}^1 P^t_s(x) P^v_u(x)dx=(-1)^delta|v-t|2^{|v-t|-2}sqrt{frac{(s+t)!(u+v)!}{(s-t)!(u-v)!}}timessum_alpha (2alpha+1)left(1+(-1)^{alpha+|v-t|}right)sqrt{frac{(alpha-|v-t|)!}{(alpha+|v-t|)!}}frac{Gammaleft(frac{alpha}{2}right)Gammaleft(frac{alpha+|v-t|+1}{2}right)}{left(frac{alpha-|v-t|}{2}right)!Gammaleft(frac{alpha+3}{2}right)},
        $$



        with the phase



        $$
        delta=left{begin{matrix} m_1 & mbox{ if } & m_2geq m_1, \ m_2 & mbox{ if } & m_2<m_1,end{matrix}right.
        $$



        and this integral will only be non-zero if
        $$
        (|s-u|leqalphaleq s+u)wedge(alphageq|v-t|)wedge(alpha + s + umbox{ is even}).
        $$



        Note that there is nothing specifying that $tneq v$ or $sneq u$, so this formula may simplify a little under those assumption, I haven't checked.






        share|cite|improve this answer









        $endgroup$



        I think your answer is in the paper, "The overlap integral of three associated Legendre polynomials" by Shi-Hai Dong and R. Lemus (2002) (https://www.sciencedirect.com/science/article/pii/S0893965902800040). The relevant expression is $I(s,t;u,v)$, given by equations (7-10), and yields



        $$
        int_{-1}^1 P^t_s(x) P^v_u(x)dx=(-1)^delta|v-t|2^{|v-t|-2}sqrt{frac{(s+t)!(u+v)!}{(s-t)!(u-v)!}}timessum_alpha (2alpha+1)left(1+(-1)^{alpha+|v-t|}right)sqrt{frac{(alpha-|v-t|)!}{(alpha+|v-t|)!}}frac{Gammaleft(frac{alpha}{2}right)Gammaleft(frac{alpha+|v-t|+1}{2}right)}{left(frac{alpha-|v-t|}{2}right)!Gammaleft(frac{alpha+3}{2}right)},
        $$



        with the phase



        $$
        delta=left{begin{matrix} m_1 & mbox{ if } & m_2geq m_1, \ m_2 & mbox{ if } & m_2<m_1,end{matrix}right.
        $$



        and this integral will only be non-zero if
        $$
        (|s-u|leqalphaleq s+u)wedge(alphageq|v-t|)wedge(alpha + s + umbox{ is even}).
        $$



        Note that there is nothing specifying that $tneq v$ or $sneq u$, so this formula may simplify a little under those assumption, I haven't checked.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Dec 9 '18 at 0:03









        Pan DaemoniumPan Daemonium

        526




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