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1: 18.3 Definitions
§18.3 Definitions
Table 18.3.1: Orthogonality properties for classical OP’s: intervals, weight functions, standardizations, leading coefficients, and parameter constraints. …
Name p n ( x ) ( a , b ) w ( x ) h n k n k ~ n / k n Constraints
Jacobi P n ( α , β ) ( x ) ( 1 , 1 ) ( 1 x ) α ( 1 + x ) β 𝒜 n ( n + α + β + 1 ) n 2 n n ! n ( α β ) 2 n + α + β α , β > 1
For expressions of ultraspherical, Chebyshev, and Legendre polynomials in terms of Jacobi polynomials, see §18.7(i). … For 1 β > α > 1 a finite system of Jacobi polynomials P n ( α , β ) ( x ) is orthogonal on ( 1 , ) with weight function w ( x ) = ( x 1 ) α ( x + 1 ) β . For ν and N > 1 2 a finite system of Jacobi polynomials P n ( N 1 + i ν , N 1 i ν ) ( i x ) (called pseudo Jacobi polynomials or Routh–Romanovski polynomials) is orthogonal on ( , ) with w ( x ) = ( 1 + x 2 ) N 1 e 2 ν arctan x . …
2: 18.7 Interrelations and Limit Relations
18.7.3 T n ( x ) = P n ( 1 2 , 1 2 ) ( x ) / P n ( 1 2 , 1 2 ) ( 1 ) ,
18.7.4 U n ( x ) = C n ( 1 ) ( x ) = ( n + 1 ) P n ( 1 2 , 1 2 ) ( x ) / P n ( 1 2 , 1 2 ) ( 1 ) ,
18.7.13 P 2 n ( α , α ) ( x ) P 2 n ( α , α ) ( 1 ) = P n ( α , 1 2 ) ( 2 x 2 1 ) P n ( α , 1 2 ) ( 1 ) ,
18.7.14 P 2 n + 1 ( α , α ) ( x ) P 2 n + 1 ( α , α ) ( 1 ) = x P n ( α , 1 2 ) ( 2 x 2 1 ) P n ( α , 1 2 ) ( 1 ) .
18.7.23 lim α α 1 2 n P n ( α , α ) ( α 1 2 x ) = H n ( x ) 2 n n ! .
3: 18.14 Inequalities
Jacobi
Jacobi
Let R n ( x ) = P n ( α , β ) ( x ) / P n ( α , β ) ( 1 ) . …
Jacobi
Szegő–Szász Inequality
4: 37.3 Triangular Region with Weight Function x α y β ( 1 x y ) γ
Jacobi polynomials on the triangle
37.3.7 P k , n α , β , γ ( x , y ) = ( 1 ) k P k , n α , γ , β ( x , 1 x y ) ,
37.3.8 Q k , n α , β , γ ( x , y ) = P k , n β , γ , α ( y , 1 x y ) = ( 1 ) k P k , n β , α , γ ( y , x ) = P n k ( 2 k + α + γ + 1 , β ) ( 2 y 1 ) ( 1 y ) k P k ( α , γ ) ( 1 2 x 1 y ) ,
37.3.9 R k , n α , β , γ ( x , y ) = P k , n γ , α , β ( 1 x y , x ) = ( 1 ) k P k , n γ , β , α ( 1 x y , y ) = P n k ( 2 k + α + β + 1 , γ ) ( 1 2 x 2 y ) ( x + y ) k P k ( β , α ) ( x y x + y ) ,
The first expression for U k , n α , β , γ in (37.3.12) is an analogue of the Rodrigues formulas in §18.5(ii). …
5: 18.6 Symmetry, Special Values, and Limits to Monomials
Table 18.6.1: Classical OP’s: symmetry and special values.
p n ( x ) p n ( x ) p n ( 1 ) p 2 n ( 0 ) p 2 n + 1 ( 0 )
P n ( α , β ) ( x ) ( 1 ) n P n ( β , α ) ( x ) ( α + 1 ) n / n !
P n ( α , α ) ( x ) ( 1 ) n P n ( α , α ) ( x ) ( α + 1 ) n / n ! ( 1 4 ) n ( n + α + 1 ) n / n ! ( 1 4 ) n ( n + α + 1 ) n + 1 / n !
§18.6(ii) Limits to Monomials
18.6.2 lim α P n ( α , β ) ( x ) P n ( α , β ) ( 1 ) = ( 1 + x 2 ) n ,
18.6.3 lim β P n ( α , β ) ( x ) P n ( α , β ) ( 1 ) = ( 1 x 2 ) n ,
6: 18.4 Graphics
See accompanying text
Figure 18.4.1: Jacobi polynomials P n ( 1.5 , 0.5 ) ( x ) , n = 1 , 2 , 3 , 4 , 5 . Magnify
See accompanying text
Figure 18.4.2: Jacobi polynomials P n ( 1.25 , 0.75 ) ( x ) , n = 7 , 8 . This illustrates inequalities for extrema of a Jacobi polynomial; see (18.14.16). … Magnify
7: 18.9 Recurrence Relations and Derivatives
For p n ( x ) = P n ( α , β ) ( x ) , … For p n ( x ) = P n ( α , β ) ( x ) , …
18.9.3 P n ( α , β 1 ) ( x ) P n ( α 1 , β ) ( x ) = P n 1 ( α , β ) ( x ) ,
18.9.4 ( 1 x ) P n ( α + 1 , β ) ( x ) + ( 1 + x ) P n ( α , β + 1 ) ( x ) = 2 P n ( α , β ) ( x ) ,
Jacobi
8: 37.4 Disk with Weight Function ( 1 x 2 y 2 ) α
37.4.4 const . P n k ( α + k + 1 2 , α + k + 1 2 ) ( x ) ( 1 x 2 ) 1 2 k P k ( α , α ) ( y 1 x 2 )
For Jacobi polynomial P n ( α , β ) ( x ) in one variable, given in Table 18.3.1, we will use the standardization
R n ( α , β ) ( x ) = P n ( α , β ) ( x ) P n ( α , β ) ( 1 ) ,
R n ( α , β ) ( 1 ) = 1 .
Then, for k 0 , the polynomials R n ( α , k ) ( 2 x 1 ) are orthogonal on ( 0 , 1 ) with weight function ( 1 x ) α x k . …
9: 18.10 Integral Representations
18.10.1 P n ( α , α ) ( cos θ ) P n ( α , α ) ( 1 ) = C n ( α + 1 2 ) ( cos θ ) C n ( α + 1 2 ) ( 1 ) = 2 α + 1 2 Γ ( α + 1 ) π 1 2 Γ ( α + 1 2 ) ( sin θ ) 2 α 0 θ cos ( ( n + α + 1 2 ) ϕ ) ( cos ϕ cos θ ) α + 1 2 d ϕ , 0 < θ < π , α > 1 2 .
Generalizations of (18.10.1) for P n ( α , β ) are given in Gasper (1975, (6),(8)) and Koornwinder (1975a, (5.7),(5.8)). …
Jacobi
18.10.4 P n ( α , α ) ( cos θ ) P n ( α , α ) ( 1 ) = C n ( α + 1 2 ) ( cos θ ) C n ( α + 1 2 ) ( 1 ) = Γ ( α + 1 ) π 1 2 Γ ( α + 1 2 ) 0 π ( cos θ + i sin θ cos ϕ ) n ( sin ϕ ) 2 α d ϕ , α > 1 2 .
Table 18.10.1: Classical OP’s: contour integral representations (18.10.8).
p n ( x ) g 0 ( x ) g 1 ( z , x ) g 2 ( z , x ) c Conditions
P n ( α , β ) ( x ) ( 1 x ) α ( 1 + x ) β z 2 1 2 ( z x ) ( 1 z ) α ( 1 + z ) β x ± 1 outside C .
10: 18.12 Generating Functions
Jacobi
18.12.1 2 α + β R ( 1 + R z ) α ( 1 + R + z ) β = n = 0 P n ( α , β ) ( x ) z n , R = 1 2 x z + z 2 , | z | < 1 ,
18.12.3 ( 1 + z ) α β 1 F 1 2 ( 1 2 ( α + β + 1 ) , 1 2 ( α + β + 2 ) β + 1 ; 2 ( x + 1 ) z ( 1 + z ) 2 ) = n = 0 ( α + β + 1 ) n ( β + 1 ) n P n ( α , β ) ( x ) z n , | z | < 1 ,
18.12.3_5 1 + z ( 1 2 x z + z 2 ) β + 3 2 = n = 0 ( 2 β + 2 ) n ( β + 1 ) n P n ( β + 1 , β ) ( x ) z n , | z | < 1 ,
18.12.4 ( 1 2 x z + z 2 ) λ = n = 0 C n ( λ ) ( x ) z n = n = 0 ( 2 λ ) n ( λ + 1 2 ) n P n ( λ 1 2 , λ 1 2 ) ( x ) z n , | z | < 1 .