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JacobiP

Jacobi function Calling Sequence JacobiP(n, a, b, x) Parameters

 n - algebraic expression a - algebraic expression b - algebraic expression x - algebraic expression Description

 • If the first parameter is a non-negative integer, the JacobiP(n, a, b, x) function computes the nth Jacobi polynomial with parameters a and b evaluated at x.
 • These polynomials are orthogonal on the interval $\left[-1,1\right]$ with respect to the weight function $w\left(x\right)={\left(1-x\right)}^{a}{\left(1+x\right)}^{b}$ when a and b are greater than -1. They satisfy the following:

${\int }_{-1}^{1}{P}_{m}^{\left(a,b\right)}\left(x\right)\phantom{\rule[-0.0ex]{0.5ex}{0.0ex}}{P}_{n}^{\left(a,b\right)}\left(x\right)\phantom{\rule[-0.0ex]{0.5ex}{0.0ex}}w\left(x\right)\phantom{\rule[-0.0ex]{0.5ex}{0.0ex}}&d;x\phantom{\rule[-0.0ex]{0.5ex}{0.0ex}}=\left\{\begin{array}{cc}0& n\ne m\\ \frac{{2}^{a+b+1}\phantom{\rule[-0.0ex]{0.5ex}{0.0ex}}\mathrm{\Gamma }\left(n+a+1\right)\phantom{\rule[-0.0ex]{0.5ex}{0.0ex}}\mathrm{\Gamma }\left(n+b+1\right)}{\left(2n+a+b+1\right)\phantom{\rule[-0.0ex]{0.5ex}{0.0ex}}\mathrm{\Gamma }\left(n+a+b+1\right)\phantom{\rule[-0.0ex]{0.5ex}{0.0ex}}n!}& n=m\end{array}$

 • The polynomials satisfy the following recurrence relation:

$\mathrm{JacobiP}\left(0,a,b,x\right)=1$

$\mathrm{JacobiP}\left(1,a,b,x\right)=\frac{a}{2}-\frac{b}{2}+\left(1+\frac{a}{2}+\frac{b}{2}\right)x$

$\mathrm{JacobiP}\left(n,a,b,x\right)=\frac{\left(2n+a+b-1\right)\left({a}^{2}-{b}^{2}+\left(2n+a+b-2\right)\left(2n+a+b\right)x\right)\mathrm{JacobiP}\left(n-1,a,b,x\right)}{2n\left(n+a+b\right)\left(2n+a+b-2\right)}-\frac{\left(n+a-1\right)\left(n+b-1\right)\left(2n+a+b\right)\mathrm{JacobiP}\left(n-2,a,b,x\right)}{n\left(n+a+b\right)\left(2n+a+b-2\right)},\mathrm{for n > 1.}$

 • For n and not equal to a non-negative integer and a not a negative integer, the analytic extension of the Jacobi polynomial is given by the following:

$\mathrm{JacobiP}\left(n,a,b,x\right)=\left(\genfrac{}{}{0}{}{a+n}{a}\right)\mathrm{hypergeom}\left(\left[-n,a+b+n+1\right],\left[a+1\right],\frac{1}{2}-\frac{x}{2}\right)$ Examples

 > $\mathrm{JacobiP}\left(4,1,\frac{3}{4},x\right)$
 ${\mathrm{JacobiP}}{}\left({4}{,}{1}{,}\frac{{3}}{{4}}{,}{x}\right)$ (1)
 > $\mathrm{simplify}\left(,'\mathrm{JacobiP}'\right)$
 $\frac{{19075}}{{32768}}{-}\frac{{3915}}{{8192}}{}{x}{-}\frac{{129735}}{{16384}}{}{{x}}^{{2}}{+}\frac{{9765}}{{8192}}{}{{x}}^{{3}}{+}\frac{{380835}}{{32768}}{}{{x}}^{{4}}$ (2)
 > $\mathrm{JacobiP}\left(2.2,1,\frac{2}{3},0.4\right)$
 ${-0.1993478307}$ (3) Compatibility

 • The JacobiP command was updated in Maple 2020.