Content-Length: 275439 | pFad | https://dlmf.nist.gov/./././././././.././../././10.49#ii
DLMF: §10.49 Explicit Formulas ‣ Spherical Bessel Functions ‣ Chapter 10 Bessel Functions
§10.49 Explicit Formulas
Contents
§10.49(i) Unmodified Functions
§10.49(ii) Modified Functions
§10.49(iii) Rayleigh’s Formulas
§10.49(iv) Sums or Differences of Squares
§10.49(i) Unmodified Functions
Define a k ( ν ) as in (10.17.1 ). Then
10.49.1
a k ( n + 1 2 ) = { ( n + k ) ! 2 k k ! ( n − k ) ! , k = 0 , 1 , … , n , 0 , k = n + 1 , n + 2 , … .
10.49.2
𝗃 n ( z ) = sin ( z − 1 2 n π ) ∑ k = 0 ⌊ n / 2 ⌋ ( − 1 ) k a 2 k ( n + 1 2 ) z 2 k + 1 + cos ( z − 1 2 n π ) ∑ k = 0 ⌊ ( n − 1 ) / 2 ⌋ ( − 1 ) k a 2 k + 1 ( n + 1 2 ) z 2 k + 2 .
10.49.3
𝗃 0 ( z )
= sin z z ,
𝗃 1 ( z )
= sin z z 2 − cos z z ,
𝗃 2 ( z )
= ( − 1 z + 3 z 3 ) sin z − 3 z 2 cos z .
10.49.4
𝗒 n ( z ) = − cos ( z − 1 2 n π ) ∑ k = 0 ⌊ n / 2 ⌋ ( − 1 ) k a 2 k ( n + 1 2 ) z 2 k + 1 + sin ( z − 1 2 n π ) ∑ k = 0 ⌊ ( n − 1 ) / 2 ⌋ ( − 1 ) k a 2 k + 1 ( n + 1 2 ) z 2 k + 2 .
10.49.5
𝗒 0 ( z )
= − cos z z ,
𝗒 1 ( z )
= − cos z z 2 − sin z z ,
𝗒 2 ( z )
= ( 1 z − 3 z 3 ) cos z − 3 z 2 sin z .
10.49.6
𝗁 n ( 1 ) ( z )
= e i z ∑ k = 0 n i k − n − 1 a k ( n + 1 2 ) z k + 1 ,
10.49.7
𝗁 n ( 2 ) ( z )
= e − i z ∑ k = 0 n ( − i ) k − n − 1 a k ( n + 1 2 ) z k + 1 .
§10.49(ii) Modified Functions
Again, with a k ( n + 1 2 ) as in (10.49.1 ),
10.49.8
𝗂 n ( 1 ) ( z ) = 1 2 e z ∑ k = 0 n ( − 1 ) k a k ( n + 1 2 ) z k + 1 + ( − 1 ) n + 1 1 2 e − z ∑ k = 0 n a k ( n + 1 2 ) z k + 1 .
10.49.9
𝗂 0 ( 1 ) ( z )
= sinh z z ,
𝗂 1 ( 1 ) ( z )
= − sinh z z 2 + cosh z z ,
𝗂 2 ( 1 ) ( z )
= ( 1 z + 3 z 3 ) sinh z − 3 z 2 cosh z .
10.49.10
𝗂 n ( 2 ) ( z ) = 1 2 e z ∑ k = 0 n ( − 1 ) k a k ( n + 1 2 ) z k + 1 + ( − 1 ) n 1 2 e − z ∑ k = 0 n a k ( n + 1 2 ) z k + 1 .
10.49.11
𝗂 0 ( 2 ) ( z )
= cosh z z ,
𝗂 1 ( 2 ) ( z )
= − cosh z z 2 + sinh z z ,
𝗂 2 ( 2 ) ( z )
= ( 1 z + 3 z 3 ) cosh z − 3 z 2 sinh z .
10.49.12
𝗄 n ( z ) = 1 2 π e − z ∑ k = 0 n a k ( n + 1 2 ) z k + 1 .
10.49.13
𝗄 0 ( z )
= 1 2 π e − z z ,
𝗄 1 ( z )
= 1 2 π e − z ( 1 z + 1 z 2 ) ,
𝗄 2 ( z )
= 1 2 π e − z ( 1 z + 3 z 2 + 3 z 3 ) .
∑ k = 0 n a k ( n + 1 2 ) z n − k is sometimes called the
Bessel polynomial of degree n . For a survey of properties of these
polynomials and their generalizations see Grosswald (1978 ) . See also
§18.34 , de Bruin et al. (1981a , b ) , and
Dunster (2001c ) .
§10.49(iii) Rayleigh’s Formulas
10.49.14
𝗃 n ( z )
= z n ( − 1 z d d z ) n sin z z ,
𝗒 n ( z )
= − z n ( − 1 z d d z ) n cos z z .
10.49.15
𝗂 n ( 1 ) ( z )
= z n ( 1 z d d z ) n sinh z z ,
𝗂 n ( 2 ) ( z )
= z n ( 1 z d d z ) n cosh z z .
10.49.16
𝗄 n ( z ) = ( − 1 ) n 1 2 π z n ( 1 z d d z ) n e − z z .
§10.49(iv) Sums or Differences of Squares
Denote
10.49.17
s k ( n + 1 2 ) = ( 2 k ) ! ( n + k ) ! 2 2 k ( k ! ) 2 ( n − k ) ! ,
k = 0 , 1 , … , n .
Then
10.49.18
𝗃 n 2 ( z ) + 𝗒 n 2 ( z ) = ∑ k = 0 n s k ( n + 1 2 ) z 2 k + 2 .
10.49.19
𝗃 0 2 ( z ) + 𝗒 0 2 ( z )
= z − 2 ,
𝗃 1 2 ( z ) + 𝗒 1 2 ( z )
= z − 2 + z − 4 ,
𝗃 2 2 ( z ) + 𝗒 2 2 ( z )
= z − 2 + 3 z − 4 + 9 z − 6 .
10.49.20
( 𝗂 n ( 1 ) ( z ) ) 2 − ( 𝗂 n ( 2 ) ( z ) ) 2 = ( − 1 ) n + 1 ∑ k = 0 n ( − 1 ) k s k ( n + 1 2 ) z 2 k + 2 .
10.49.21
( 𝗂 0 ( 1 ) ( z ) ) 2 − ( 𝗂 0 ( 2 ) ( z ) ) 2
= − z − 2 ,
( 𝗂 1 ( 1 ) ( z ) ) 2 − ( 𝗂 1 ( 2 ) ( z ) ) 2
= z − 2 − z − 4 ,
( 𝗂 2 ( 1 ) ( z ) ) 2 − ( 𝗂 2 ( 2 ) ( z ) ) 2
= − z − 2 + 3 z − 4 − 9 z − 6 .