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9 . Bessel Functions of Integer Order F . W . J . OLVER~ Con tents Page Mathematical Properties .................... 358 Notation ........................... 358 Bessel Functions J and Y ................... 358 9.1. Definitions and Elementary Properties ......... 358 9.2. Asymptot.ic Expansions for Large Arguments ...... 364 9.3. Asymptotic Expansions for Large Orders ........ 365 9.4. Polynomial Approximations .............. 369 9.5. Zeros ........................ 370 374 9.6. Definitions and Properties . . . . . . . . . . . . . . 374 9.7. Asymptotic Expansions ................ 377 9.8. Polynomial Approximations .............. 378 Kelvin Functions ....................... 379 379 9.11. Polynomial Approximations ............. 384 Numerical Methods ...................... 385 9.12. Use and Extension of the Tables ........... 385 References ........................... 388 Table 9.1. Bessel Functions-Orders 0. 1. and 2 (0 5~517.5) .... 390 Modified Bessel Functions I and K ............... 9.9. Definitions and Properties .............. 9.10. Asymptotic Expansions ............... 381 Jo(x). 15D. Ji@). J&). Yob). YI(~). 10D Yz(x), 8D ~=0(.1)17.5 Bessel Functions-Modulus and Phase of Orders 0. 1. 2 (1O~s_<~) .................... 396 dMn(x). 6, (z) -z. 8D n=0(1)2,2-'=.1(-.01)0 Bessel Functions-Auxiliary Table for Small Arguments 2 2 (05x52) ..................... 397 Yo(+; Jo(4 In z, Z[Y1(2)-; JI(4 21 ~=0(.1)2, 8D Table 9.2. Bessel Functions-Orders 3-9 (0 52120) ........ 398 Jn 7 Yn 9 n=3 (1)s 2=0(.2)20, 5D or 5s National Bureau of Standards. on leave from the National Physical Laboratory . 355
Transcript
Page 1: Bessel functionsofintegerorder1

9 . Bessel Functions of Integer Order F . W . J . OLVER~

Con tents

Page Mathematical Properties . . . . . . . . . . . . . . . . . . . . 358

Notation . . . . . . . . . . . . . . . . . . . . . . . . . . . 358 Bessel Functions J and Y . . . . . . . . . . . . . . . . . . . 358

9.1. Definitions and Elementary Properties . . . . . . . . . 358 9.2. Asymptot.ic Expansions for Large Arguments . . . . . . 364 9.3. Asymptotic Expansions for Large Orders . . . . . . . . 365 9.4. Polynomial Approximations . . . . . . . . . . . . . . 369 9.5. Zeros . . . . . . . . . . . . . . . . . . . . . . . . 370

374 9.6. Definitions and Properties . . . . . . . . . . . . . . 374 9.7. Asymptotic Expansions . . . . . . . . . . . . . . . . 377 9.8. Polynomial Approximations . . . . . . . . . . . . . . 378

Kelvin Functions . . . . . . . . . . . . . . . . . . . . . . . 379 379

9.11. Polynomial Approximations . . . . . . . . . . . . . 384 Numerical Methods . . . . . . . . . . . . . . . . . . . . . . 385

9.12. Use and Extension of the Tables . . . . . . . . . . . 385 References . . . . . . . . . . . . . . . . . . . . . . . . . . . 388 Table 9.1. Bessel Functions-Orders 0. 1. and 2 (0 5 ~ 5 1 7 . 5 ) . . . . 390

Modified Bessel Functions I and K . . . . . . . . . . . . . . .

9.9. Definitions and Properties . . . . . . . . . . . . . . 9.10. Asymptotic Expansions . . . . . . . . . . . . . . . 381

Jo(x). 15D. Ji@). J&). Yob). YI(~). 10D Yz(x), 8D ~=0(.1)17.5

Bessel Functions-Modulus and Phase of Orders 0. 1. 2 ( 1 O ~ s _ < ~ ) . . . . . . . . . . . . . . . . . . . . 396 dMn(x). 6, (z) -z. 8D n=0(1)2,2-'=.1(-.01)0

Bessel Functions-Auxiliary Table for Small Arguments

2 2 (05x52) . . . . . . . . . . . . . . . . . . . . . 397

Yo(+; Jo(4 In z, Z[Y1(2)-; J I ( 4 21

~=0(.1)2, 8D

Table 9.2. Bessel Functions-Orders 3-9 (0 52120) . . . . . . . . 398 Jn 7 Yn 9 n=3 (1)s 2=0(.2)20, 5D or 5 s

National Bureau of Standards. on leave from the National Physical Laboratory .

355

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356 BESSEL FTJNCTIONS OF INTEGER ORDER

Table 9.3. Bessel Functions-Orders 10, 11,20, and 21 ( 0 5 ~ 1 2 0 ) . . 2-*0J1o(x), z-l'J11 (z), z'"1o(z)

JlO(Z>, Jll(4, YlO(Z>

2-'0J20(2), 2-21J21(z), 2 V 2 0 ( 2 )

z=O(.l)lO, 8s or 9 s

2=10(.1)20, 8D

z=0(.1)20, 6s or 7s Bessel Functions-Modulus and Phase of Orders 10,11,20,

and 21 ( 2 0 5 ~ 5 Q)). . . . . . . . . . . . . . . . . zQ&dz), e n ( 4 -2 n=10, 11, 8D n=20, 21, 6D z-'= .05 (- .002)0

Table 9.4. Bessel Functions-Various Orders (OIn1100). . . . . . Jn(z), Y&), n=0(1)20(10)50, 100 z=1, 2, 5, 10, 50, 100, 10s

Table 9.5. Zeros and Associated Values of Bessel Functions and Their Derivatives (Osn18, 1 5 ~ 1 2 0 ) . . . . . . . . . . . j w , JX.in.8) ; j ;*s, Jn(j;,8), 5D (10D for n=o> ynS8, WynJ; Y ; . ~ , YJY;,~), 5D (8D for n=o> s=1(1)20, n=0(1)8

Table 9.6. Bessel Functions Jo(jo.,z), s= 1 (1)5 . . . . . . . . . . .

Table 9.7. Bessel Functions-Miscellaneous Zeros (s=1(1)5) . . . . .

z=O(.O2)1, 5D

8th zero of z J1 (2) - Wdz)

8th zero of Jl(z) -Wo(z)

8th zero of Jo(z) Yo(Az) - Yo(z)Jo(Az)

8th zero of Jl(z) Yl(Az) - Y,(z)J1(Az)

8th zero of J1(z) Yo(Az) - Yl(z)Jo(Az)

X, X-'=O(.O2) .I, .2(.2)1, 4D

X= .5 (. 1) 1, X-'= 1 (- .2) .2, .I (- .O2) 0, 4D

X-'=.8(-.2) .2, .1(-.02)0, 5D (8D for s=1)

X-l=.8(--.2) .2, .1(-.02)0, 5D (8D for s=1)

X-'=.8(--.2) .2, .1(-.02)0, 5D (8D for s=1)

e-zlo(z), ezKo(z), e+ll( z), ezKl(z) z=O(.l) lO (.2)20, 10D or 10s Z-~Z(~), 2Kab) ~=0(.1)5, 10D, 9D e-zla (2) , e'& (5)

z=5(.1)10 (.2)20, 9D, 8D

Table 9.8. Modified Bessel Functions of Orders 0, 1, and 2 (0 12120) .

Modified Bessel Functions-Auxiliary Table for Large Arguments ( 2 0 5 ~ 5 Q)) . . . . . . . . . . . . . . . de-zln(z), n-ldeZK.(z), n=O, 1, 2 z-'= .05( - .002)0, 8-9D

Modified Bessel Functions-Auxiliary Table for Small Arguments ( 0 5 ~ 1 2 ) . . . . . . . . . . . . . . . .

Ko(z)+Io(4 lnz, 4&(4--11(4 hzl z=0(.1)2, 8D

Page 402

406

407

409

413

414

416

422

422

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BESSEL FUNCTIONS OF INTEGER ORDER

Table 9.9. Modified Bessel Functions-Orders 3-9 (O<z<20) . . . e-”1,(z), e”K,(z), n= 3 (1)9 Z= O( .2) 10 (.5)20, 5s

Table 9.10. Modified Bessel Functions-Orders 10, 11, 20 and 21 (O<S<20) . . . . . . . . . . . . . . . . . . . .

z-’Ol10(z), z-11111(2), zloKlo(z) z=0(.2)10, 8s or 9s e-zllo(z), e-”111(z), e”Kd4

z-zo120(z), z-z1121 (4, Z0Kz0(z) z=0(.2)20, 5s to 7s

Arguments (20 <z < a).

z=10(.2)20, 10D, lOD, 7D

Modified Bessel Functions-Auxiliary Table for Large . . . . . . . . . . . . . .

In{ z+e-zllo(z)}, ln{z+e-zIll(z)}, ln{?r-lzfeZKlo(z)} In{ z+e-zlzo(z)}, In{ z+e-zlzl(z)}, ln{r-lz’eZKzo(z)} ~-‘=.05(-.001)0, SD, 6D

Table 9.11. Modified Bessel Functions-Various Orders (0 <n < 100) . In(z), K,,(z), n=0(1)20(10)50, 100 z=1, 2, 5, 10, 50, 100,

Table 9.12. Kelvin Functions-Orders 0 and 1 (O<z<5) ber z, bei z, berl 2, bei, z ker z, kei z, kerl z, keil z z=0(.1)5, IOD, 9D

9s or 10s

. . . . . .

Kelvin Functions-Auxiliary Table for Small Arguments (O<z<l). . . . . . . . . . . . . . . . . . . . . ker z+ber z In z, kei z+bei z I n z z(kerlz+berl z In z), z(kei, z+beil z I n z) z=O(.1)1, 9D

Kelvin Functions-Modulus and Phase ( 0 1 ~ 1 7 ) . . . .

Mo(4, eO(4, Ml(d, el(4 N O ( 4 , 40(4, N1(4,41(4 z=0(.2)7, 6D

Kelvin Functions-Modulus and Phase for Large Argu- ments (6.6535 a ) . . . . . . . . . . . . . . . . . z+e-”’J2Mo(z), eo(z) - (z/.\/z), z+e-Z/~Ml (z), el (z) - (z/Jz) z+ezlJ2No(z>, 40(4 + (z/.\/z>, zifez’.“N(z), $1 (2) + (z/.\/z) z-’= .15( - .Ol)O, 5D

357

Page 423

425

427

428

430

430

432

432

The author acknowledges the assistance of Alfred E. Beam, Ruth E. Capuano, Lois K. Cherwinski, Elizabeth F. Godefroy, David S. Liepman, Mary Orr, Bertha H. Walter, and Ruth Zucker of the National Bureau of Standards, and N. F. Bird, C. W. Clenshaw, and Joan M. Felton of the National Physical Laboratory in the preparation and checking of the tables and graphs.

Page 4: Bessel functionsofintegerorder1

9. Bessel Functions of Integer Order

Mathematical Properties

Notation The tables in this chapter are for Bessel func-

tions of integer order; the text treats general orders. The conventions used are:

z=z+iy; z, y real. n is a positive integer or zero. v, p are unrestricted except where otherwise

indicated; v is supposed real in the sections devoted to Kelvin functions 9.9, 9.10, and 9.11.

The notation used for the Bessel functions is that of Watson [9.15] and the British Association and Royal Society Mathematical Tables. The function Y,(z) is often denoted Nv(z) by physicists and European workers.

Aldis, Airey: Other notations are those of:

G,(z) for -+rY,(z),K,(z) for (-)*K,(z).

Clifford:

C,(z) for ~-4~J,,(2fi).

Gray, Mathews and MacRobert [9.9]:

Y,(z) for +rY,(z)+ On 2--r)J,(z),

Y,(z) for revr* sec(va) Y,(z),

0, (2) for +7riH:1) (2).

-

Jahnke, Emde and Losch [9.32]:

a&) for r (Y+ 1)( $2) - ’J, (2).

Jeff reys :

H.s,(z) for HY(z), Hi,(z) for H?)(z),

Kh,(z) for (2/a)K,(z).

Heine:

K, (2) for- ~PY, (2).

Neumann:

Yn(z) for )?rY,(z)+(ln 2--y)Jn(z).

Wbittaker and Watson [9.18]:

K,(z) for cos(vir)K,(z).

358

Bessel Functions J and Y

9.1. Definitions and Elementary Properties

Differential Equation

22-+2 d2w dw -+(22-v2)w=O 9.1.1 dz2 dz

Solutions are the Bessel functions of the f i s t kind J*.(z), of the second kind Yv(z) (also called Weber’s function) and of the third kindH$”(z), H:z)(z) (also called the Hankel functions). Each is a regular (holomorphic) function of z throughout the z-plane cut along the negative real axis, and for fixed z ( f0 ) each is an entire (integral) func- tion of v. When v= &n, Jv(z) hrts no branch point and is an entire (integral) function of z.

Important features of the various solutions are as follows: Jv(z)(9?v20) is bounded as z+O in any bounded range of arg z. Jv(z) and J-,(z) are linearly independent except when v is an integer. J.(z) and Y,(z) are linearly independent for all values of v. H!’)(z) tends to zero as IzI+- in the sector

O<arg Z<T; Hi2)(z) tends to zero as lzl--+m in the sector -r<arg z<O. For all values of v, H!”(z) and H!”(z) are linearly independent.

Relatione Between Solutions

J,(z) COS (m)- J-,(z) 9.1.2 Y,(z)= sin (m)

The right of this equation is replaced by its limiting value if v is an integer or zero.

9.1.3

Page 5: Bessel functionsofintegerorder1

BESSEL FUNCTIONS OF INTEGER ORDER 359

L I

FIGURE 9.2. Jlo(z), Ylo(x), and M o (z) = JJ:o (XI + Eo (XI.

FIGURE 9.1. Jo(z), YO@), Jl(z), Yl(z>.

’ FIGURE 9.3. J,.(lO) and y”(10)-

FIGURE 9.4. Contour lines of the modulus and phase of the Hankel Function HP(x+iy)=MoefSo. From E. Jahnke, F. Emde, and F. Losch, Tables of higher functions, McGraw-Hill Book CO., Inc., New York, N.Y., 1960 (with permission).

Page 6: Bessel functionsofintegerorder1

360 BESSEL FUNCTIONS OF INTEGER ORDER

Limiting Forms for Small Arguments

When v is fixed and z+O

9.1.7 Jv(z)-($z)v/r(V+l) (VZ-1, -2, -3, . . .)

9.1.8 Yo(z)- - iH~1)(z)~~H~2)(z)~(2/~) In z

9.1.9

YJZ) - - - i ~ : l ) (2) - i ~ : 2 ) (z) - - ( I / ~ ) r (.) ($2) -I ( 9 v >O )

Ascending Series

9.1.11

(tz”>” ($E!)-” n-1 (n-k-l)! k! Y,(z)=--

T k=O

where $(n) is given by 6.3.2.

9.1.13

Integral Representations 9.1.18

1 ’ J~ (2) =; S, cos (z sin

9.1.19

~,(z)=f I” cos (z cos e) {r+h (22 sin2 e) 1 d~

9.1.20

9.1.21

COS (zsin e-&)&

9.1.22

9.1.26

In the last integral the path of integration must lie to the left of the points t=O, 1, 2, . . . .

Page 7: Bessel functionsofintegerorder1

BESSEL FUNCTIONS OF INTEGER ORDER 361

(k=O, 1,2, . . .) 9.1.31

v v+l P.+l+T,=; p,-- b PV+l

v v+ l rv+1+qv=- b p,-- a P?+l

1 1 3 8.=2 P..+l+Z P.-I-& p,

and

9.1.34 4 pa,- qvr,=- gab

Analytic Continuation

In 9.1.35 to 9.1.38, m is an integer.

9.1.35 Jv( ze’” = em- J,( z)

9.1.36

Y,(zemrf) =e-mvrfYv(z) +2i sin(mvr) cot(vr) J,(z)

9.1.37

sin (v~)H:~) (amr f, = -sin { (m- 1) v r } H;l) (z) 9.1.38 sin(vr)H;’) (amr? =sin { (m+ 1) v r ) 23:’) (z)

9.1.39

sin(mvr) H!’) (2)

+ e v r f sin (mvr) H:’) ( z)

H!l)(zerf)= -e-vrfH$’)

H:’) (ze-rf) = -p*Hil’(z) 0

9.1.40 - -

JIG) =Jv(z) Y,G) = Yv(z)

H;l)(Z)=m) Hr) (Z )=Hm (V real)

Generating Function and Amia t ed Serier

m

9.1.41 eW-W)= t *Jk(Z) ( t W k--m

m

k = l 9.1.42 cos (z sin e) =Jo(z) +2 C Jzk(z) cos (2M)

9.1.43 sin (z sin e)=2 Jnk+l(~) sin { (2k+l)O}

9.1.44

m

k-0

m

COS (Z COS e)=Jo(z)+2 (-)kJzk(~) COS (2M) k-1

9.1.45 m

k-0 sin (z cos e)=2 (-)kJ2k+l(z) cos { (2k+l)B}

9.1.48 sin z=2J~(z)-25,(2)+2J5(z)- . . .

Page 8: Bessel functionsofintegerorder1

362 BESSEL FUNCTIONS OF INTEGER ORDER

Other Differential Equations

3- 3 9.1.49 w" 4- ( x2-- z2 )w=o, w=zQ?,(hz)

9.1.50 wf +(E--) 3-1 w=o,

9.1.51 W" +X22P-2~=0, W=Z+ %?llp(2X~fP/p)

9.1.52 2v-1

W''-- w1+X2w=O, w=z*%v(Az) Z

9.1.53 21w" + (1 - 2p)m' + (A7$9g+p=- 3$)w= 0,

9.1.54 w = ZP%,(XZ~)

w" + (A2eZ2- v2)w= 0, w = U,(Ae2)

9.1.55

2(2-v2)w"+z(z~-33)w' + { (22--3)2--(~+v~)}w=O, w=U:(z)

9.1.56

w(*n) = (-)"A2nZ-nw, w= z*'Un(2Aazj)

where a is any of the 2n roots of unity. DiEerentiaI Equations for Products

d dz In the following QE z -and U,(z), 9,(z) are any

cylinder functions of orders v, p respectively.

9.1.57 { 9 4 - 2 (v"+ s)tp2+ (9- p*yj w +422(9+ 1)(9+2)~=0, ?~=%',(z)52~(2)

9.1.58

Q(Q2-43)~+4zP(Q+1)~=0, ~=U.(z)gv(z)

9.1.59

Zaw"'+2(4~?+ 1-49)~'+(43- l)w=O, w = zU,( 2) 9 I (2)

(v 2 1) Upper Bounds

9.1.60 JJ. (2) I I 1 (V>_O), 1 J, (4 I5 I/&

Derivatives With Respect to Order 9.1.a

9.1.65

b --c9c (4 - av JJZ) -7rJ. (2)

( V Z O , f l , f 2 , . . , ) 9.1.66

9.1.67

9.1.68

Expreaaions in Terms of Hypergeometric Functions

9.1.69

9.1.70

as A, p+= through real or complex values; z, v being fixed. (oF1 is the generalized hypergeometric function.

For M(a, b, z) and F(a, b;c; z) see chapters 13 and 15.)

Connection With Legendre Functions

If p and z are fixed and v+- through real positive values

9.1.71

1 =J,,(z) (z>O)

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BESSEL F”CT1ONS

9.1.72

lim (I+”;’ (cos E)} =-4rY,(z) (~>0)

For P;’ and Q;”, see chapter 8.

Continued Fractions 9.1.73

. . . J’(4 1 1 1 J,-l(2)-2vz-’-- 2(v+1)2-’- 2(v+2)2-l-- --

-- - 34. iz2/{ y(v+1) 1 tz2/{ b+1) (v+2) 1 , . . 1- 1- 1-

Multiplication Theorem 9.1.74

m (F)*(~*-1)*(3~)* g (z) ’33 k! WPr(Xz)=X*’ c

k-0

(IX’-ll<l)

If W= J and the upper signs are taken, the restric- tion on X is unnecessary.

This theorem will furnish expansions of VWe) in terms of Y,*k(r).

Neumann’s Addition Theorems

9.1.75 %‘,(uz!d= 5 %‘,~&)Jdv) (Ivl<lul) k i - m

The restriction lvl<lul is unnecessary when %‘= J and v is an integer or zero. Special cases are

9.1.76 l=JX2 )+25 Z(2) k-1

9.1.77 2n o=c (-)*Jk(Z)JP,-*(z> +2 5 J*(z)Jz,+r(d (n2 1) k-0 k-1

9.1.78 m

Jn(2Z)=e Jr(Z)J,-i (2) 4-2 c (-)*Jdz)J,+dZ) k-0 k-1

Graf”e

9.1.79

%‘’(W) sin vX= c W,+&)J*(v) s . ka(lveftal<lul)

Gegenbauer’s

9.1.80

-- * d ~ ) - ~ , ~ ( ~ ) 2 (v+k) Wp+ t ( ~ ) JP+$v) c(x’(cos a)

cos m cos k--m

W’ k-0 U’ V

(v#O,-l , . . ., Ive**al<IuI)

OF INTEGER ORDER 363 In 9.1.79 and 9.1.80,

w=~(u2+2?-2uv cos a), u-v cos a=w cos x, v sina=w sin x

the branches being chosen so that 2o--vu and x+O as v+O. C‘X)(cos a) is Gegenbauer’s polynomial (see chapter 22).

Ge g e n hw’ s addition theorem.

If u, v are real and positive and 0 Sa S a, then w, x are real and non-negative, and the geometrical relationship of the variables is shown in the dia- gram.

Thc restrictions Ive*‘”l< 1.1 are unnecessary in 9.1.79 when g=J and ,, is an integer or zero, and in 9.1.80 when Y=J. Degenerate Form (u= 0):

9.1.81 et0 “06a=r(v)(32))-v 2 (v+k)i*J,+r(v)C:”(cos a)

k-0 ( Y Z O , -1, . . .)

Neumann’s Expansion of an Arbitrary Function in e Series of Beasel Function8

9.1.82 f(z)=aoJo(z)+2 2 aJ&) (Izl<c) k-1

where c is the distance of the nearest singularity off(z) from z=O,

9.1.83 a*=- 1 J f(t)O*(t)dt (O<C’<C) 2a-i +e’

and O,(t) is Neumann’s polynomial. is defined by the generating function

9.1.84

The latter

L=JO(z)Odt)+2 t-2 5 k-1 J&)odt> (Izl<ltl)

O,(t) isapolynomialof degreen+l in l/t; Oo(t)=l/t,

9.1.85

(n=1,2,. . .) n(n-k-l)! 2 “-a+* w - 4 -’% klo k! (t>

The more general form of expansion

j(z) =ao~.(z> +2 5 aJv+*(z) 9.1.86 k-1

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364 BESSEL F"CT1ONS OF INTEGER ORDER

also called a Neumann expansion, is investigated in [9.7] and [9.15] together with further generaliza- tions. Examples of Neumann expansions are 9.1.41 to 9.1.48 and the Addition Theorems. Other examples are

9.1.87

(VZO, -1,-2,. . .)

9.1.88 n!($z)-" n-1 (+Z>Vk(Z) Y, (2) = - -

T (n-k)k!

where +(n) is given by 6.3.2.

9.1.89

9.2. Asymptotic Expansions for Large Arguments

Principal Asymptotic Forms

When Y is fixed and lz1+co

9.2.2

Yl(4 =m

Hankel's Asymptotic Expansions

When v is k e d and 1zI+-

9.2.5

J,(z)=J-a/(rz){P(v, 2) cosx-QQ(v, 2) sinx)

( I arg 4 <*I

9.2.6 Yv(z)=~'2/(rz){P(v, z) sin x+Q(v, z) cosx}

(la% 21 < 9.2.7 H,'"(z)=,/G){P(v, z)+iQ(v, z)jefx

(-T<arg 2<2r)

9.2.8

H!2) (z) = d m { P( v, z) -iQ( v, z) }e-fx

where x=z-(+++)u and, with 4v2 denoted byp,

9.2.9

(-2a<arg z<r)

. . . + b-1) (p-9) (p-25) (p-49) - 4! (82)'

9.2.10

+ . . . -cc--l (~--~)(P-9~(cC--5) 82 3! ( 8 ~ ) ~

If v is real and non-negative and z is positive, the remainder after k terms in the expansion of P(v, z) does not exceed the (k+l)th term in absolute value and is of the same sign, provided that k>$u-f. The same is true of &(v,z, provided that k>$v-t.

Asymptotic Expaneione of Derivative8

With the conditions and notation of the pre- ceding subsection

9.2.11

J L ( z > = J ~ { --~(v, z) sinx--S(v, z) cos x}

9.2.12

Y:(z) =JG) {R (v, z) cos x- S(v, z) sin x)

(la% zl<r)

(larg zl<r> 9.2.13

H;l)'(z) = 42/(~z){iR(v, z) --S(v, z)}e'x

(-7r<arg z<2r) 9.2.14

~ ! 2 ) ' ( z )= , /m{ - - i ~ ( v , z)--~(u, z))e-'X (-2r<arg z<r)

Page 11: Bessel functionsofintegerorder1

BESSEL mCTIONS OF INTEGER ORDER 365

9.2.15

9.2.16

Modulus and Phase

For real v and positive x

9.2.17

M, = IW (4 I =.\I{ cmx) + E(2) 1 8,=arg H:’)(x)=arctan { Y,(x)/Jv(x))

9.2.18

N”=~H~”’(2)1=.\I{JL’(x)+Y:’(x)} (p, = arg Hi1) ’ (x) = arc tan { YL (x) /JL (x) }

9.2.19 J,(x)=M, cos e,, Y,(x)=M, sin e,, 9.2.20 J:(x)=N, cos (pv, Y:(x)=N, sin (pV.

entiations with respect to x. In the following relations, primes denote differ-

9.2.21 M:e: =2/(a~) xv: =2 (2- v2)/(if$)

9.2.22

9.2.23

= M;2+A4;e:2 = M:’ +4/(rxMy)’

(2 -v2)MPM~+ZN,N: + XX =O 9.2.24

tan ((py - 0 . ) = M,O:/M: = 2/(axMyM~) M,N,sin ((pV-e,)=2/(ax)

9-2-25 2M;’ + xM: + (2 - P)Mv-4/(11.2M:) =O 9.2.26 2w”’tx(42+ 1-4v2)w’+ (4v2- l)w=O, w=xM

Asymptotic Expansions of Modulus and Phase

When v is fixed, xis large and positive, and p=4v2

9.2.28

9.2.29

(p- 1) (p-25) (p-1) (p2- 114p+1073) 5 (42) +

+ 6 ( 4 ~ ) ~

+ (p- 1) (5p3- 1535p2+54703p-375733) + . . . 14 (4.)’

9.2.30

X--{1-- 2 1 p-3 --- 1 . 1 (c’-l)(Cc-45)-*. * ) ax 2 (2x12 2 . 4 (2x14

The general term in the last expansion is given by

1 - 1 3 . . . (2k-3) - 2 . 4 - 6 . . . (2k)

(p-l)(p-9). . .{/~-(2k-33)~}{p-(2k+1)(2k-l)~} (22) 2k X

9.2.31

p+3 p2+46p-63 qJ”-X-(+v-;) if+-+ 2(4x) 6 ( 4 ~ ) ~

+ . . .

If v 20, the remainder after k terms in 9.2.28 does not exceed the (k+l)th term in absolute value and is of the same sign, provided that k>v-$.

p3+ 185p2-2053p$ 1899 5 (42) +

9.3. Asymptotic Expansions for Large Orders

Principal Asymptotic Forms

In the following equations it is supposed that v+ OJ through real positive values, the other vari- ables being fixed.

9.3.1

9.3.2 ,v(tsnh a-a)

Page 12: Bessel functionsofintegerorder1

BESSEL FUNCTIONS OF INTEGER ORDER 366

9.3.3

J. (v sec @) =

J2/(7rv tan 8) {cos (v tan p- vp- &) + O (v-1) } <o<a<a*>

J2/(?rv tan @) {sin (v tan p-vp-$n)+O(v-*)}

(O<P<h)

Y.(v sec p)=

9.3.4 J& + ZV%) = 2%-46 Ai( - 2542) + O(v-l)

Y,(v+zvB)=-2!%-H Bi(-Pz) +O(v-l)

9.3.5

2% 1 Y&)--- - 3W ($) d 4

In the last two equations { is gL *Ten I y 9.3.38 and 9.3.39 below.

Debye's Asymptotic Expansions

(i) If a is fixed and positive and v is large and positive

9.3.7

9.3.8

Y,(v sech a)-

where

9.3.9 uo(t)=l ~l(t)=(3t-5t?/24 UZ (t) == (8 lt2-462t4+ 385t6)/l 152 u3(t)=(3O375t3-3 69603t5+7 65765t7

~ 4 ( t ) = (44 651255'- 941 21676ts+3499 22430t' -4 25425t9)/4 14720

-4461 85740t"+ 1859 10725t12)/398 13120

For u5(t) and u,(t) see [9.4] or [9.21].

9.3.10 Uk+l(t) = it'( 1- tz)>d (t) +g 1 ' (1-5t2)u,(f)dt

0

(k=O, 1, . . .) Also

9.3.11

J:(v sech a) -

9.3.12 Y:(v sech a)

1 k = l

where

9i3.13 vo(t)=l v,(t)= (-9t+7f!)/24 vz(t) = (- 135% + 594t'-455te)/1 152 v3(t)=(-42525t3+4 51737t'-8 83575P

9.3.14 4-4 75475t9)/4 14720

vk(t)=uk(t)+t(t2-1){ ~uk-l(t)+tu~-l(t)} (k=1, 2, . . .)

(ii) If p is fixed, O<p<$r and v is large and positive

9.3.17

=I- 81 cot2 8+462 cot' 84-385 cot6 B + . . . 11529

Page 13: Bessel functionsofintegerorder1

BESSEL FUNCTIONS OF INTEGER ORDER 367

9.3.18

. . . - 3 cot ~ + 5 cot3 B - - 24v

Also

9.3.20 ~ : ( v sec 0) =.J(sin 20)/(rv){ N(v, 8) cos P

where

9.3.21

-O(Y, 8) sin e}

. . . 135 cot2 /3+594 cot' 84-455 cot8 B - 11529 =1+

9.3.22

Asymptotic Expansions in the Transition Regions

When z is fixed, I v I is large and larg vI<b 9.3.23

OD fk(z> 21/3 J . ( ~ + z v ' / ~ ) - ~ Ai (-21/3~) {1+2 -p}

22/3 gk(z) +v Ai' (-2%) - k;IO VZkl3

9.3.24

Y , ( V + Z V ~ ~ ~ ) - - ~ 2113 Bi (-2ll3z) { l+C---) OD fk(z) k-1 V*I3

22/3 -- Bit (-21/3z) 2 &@ V k-0 Val3

where

9.3.25 1 5 jl(Z) = -- z

3 j*(z)=-i@ z6+-22 35

957 173 1 7000 3150 225

j3(z) =- z8- - z3--

j ( )-- 27 z10-- 23573 z7+- 5903 z4+- 947 20000 147000 138600 346500 4 2 -

9.3.26

17 1 70 70 gl(z)=-- z3+-

549 110767 z5+- 79 z2 g3(~)=- z8-- 28000 693000 12375

The corresponding expansions for (Y+ z ~ ~ / ~ ) and H!a)(v+~v1/3) are obtained by use of 9.1.3 and 9.1.4; they are valid for --)r<arg v<#r and -#?r<arg v<+r, respectively.

9.3.27

22/3 (ID hk(z) J:(v+zv~/~) --y2/3 Ai' (-2ll3z) { 1+c -) k = l V

9.3.28

hdz) 2213 Y:(v+ zV1I3) - y2/3 Bi' (-2ll3z) { 1+C k-1 -} V where

9.3.29

57 100 70 I&)=-- z5+- 22

699 2617 23 h3(~)=- z8-- z3+- 3500 3150 3150

27 46631 $+- 3889 z4-- 1159 20000 147000 4620 115500 h4(z)=- z"--

9.3.30

3 1 I0(z) =5 z3-%

I, (2) = - - 13' z4+l 140 5 9 28+- 5437 z5-- 593 z2 &(z) = - -

&(z)=- z9-- z8+- z3+-

500 4500 3150 369 999443 31727 947 7000 693000 173250 346500

Page 14: Bessel functionsofintegerorder1

368 BESSEL FUNCTIONS

3ll2b 'Yk 9.3.34 Y:(v) -7 { 1 +c 5 k= l v

where

2113 a=-=.44730 73184, 3+a= .77475 90021 321317 ($1

31f3r(g)- 2213

b=--.41085 01939, 3*b=.71161 34101

ffo=l, cy1=--=- .004, 225

~r2=.00069 3735 . . ., ~~3=-.00035 38 . . +

1 Bo=7q=.O1428 57143. . .,

1213 =-.00118 48596.. ., 'l=-10 23750

&=.00043 78 . . ., &=-.OOO38 . . . 23 3150 */o=I, 71=-=.00730 15873 . 1 .,

yz=- .00093 7300 . . .,

1 947

62= .00060 47 . . . ,

7 3 = .00044 40 . . .

.00273 30447 . . ., 6,'5, - ~ = - 3 46500

63= - .00038 . . .

Uniform Asymptotic Expansions

These are more powerful than the previous ex- pansions of this section, save for 9.3.31 and 9.3.32, but their coefficients are more complicated. They reduce to 9.3.31 and 9.3.32 when the argument equals the order.

9.3.35

Ai'(v2I3{) bk({) + v5/3 2 7 1

9.3.36

IF INTEGER ORDER

9.3.37

e2ri13Ai I (e2ri13v2f3 bd l ) + v5/3 %-I k=O V*

When v++ m , these expansions hold uniformly with respect to z in the sector larg z] 5 ?r- e, where e is an arbitrary positive number. The corre- sponding expansion for H?'(vz) is obtained by changing the sign of i in 9.3.37.

Here

9.3.38

equivalently,

9.3.39

the branches being chosen so that { is real when z is positive. The coefficients are given by

9.3.41 6s f l

9 p,=-- A, (284-1) (2~+3) . . . (68-1)

s! (144)' 6s- 1 ha=

Thus a,,({) = 1,

9.3.42 5 1 5 1

5 1 5 1

bo({) =-=+? 124(1 -z2)3/2-8(1 - z2)i 1

1 =-- 48l2+(-s)i '24(z2- 1)312+8(~2- 1))

Tables of the early coefficients are given below. For more extensive tables of the coefficients and for bounds on the remainder terms in 9.3.35 and 9.3.36 see t9.381.

Page 15: Bessel functionsofintegerorder1

BESSEL FUNCTIONS OF INTEGER ORDER 369

Uniform Expansions of the Derivatives

With the conditions of the preceding subsection

9.3.4!3

where

9.3.46 2kS1

8=0 ck({)=-r* C ~ ~ { - ~ ~ / ~ v 2+ ~+ 1 ( (1--2)-tl

d&) =E ia{-3sflv2k-x{ (1 -z2)-t} 2k

8 =O

and vk is given by 9.3.13 and 9.3.14. For bounds on the remainder terms in 9.3.43 and 9.3.44 see [ 9.381.

1

0 1 2 3 4 5 6 7 8 9

10

--r

0 1 2 3 4 5 6 7 8 9

10

0.0180 .0278 . 0351 . 0366 .0352 .0331 .0311 . 0294 . 0278 . 0265 .0253

bo(r)

0.0180 .0109 . 0067 . 0044 . 0031 .0022 . 0017 . 0013 fool1 .0009 .0007

a1 (r)

-0. 004 -. 004 -. 001 +. 002

.003

. 004

. 004

.004

.004

. 004

.004

a1 (I)

-0.004 -. 003 -. 002 -. 001 -. 001 -. 000 -. 000 -. 000 -. 000 -. 000 -. 000

Gd-r)

0. 1587 . 1785 . 1862 . 1927 .2031 . 2155 . 2284 . 2413 . 2539 . 2662 . 2781

d-r)

0. 1587 . 1323 . 1087 . 0903 .0764 . 0658 . 0576 . 0511 .0459 . 0415 . 0379

di (r)

0. 007 . 009 .007 .005 .004 .003 . 003 .003 . 003 . 003 . 003

0. 007 .004 . 002 . 001 . 001 . 000 . 000 . 000 . 000 . 000 .om

Co({)"-pj 1 p+.146{-', d,({)=.OO3.

For {<-lo use

1 bo(t))"z r2, a1(f)=.000,

CO@) " - -pj {- - 1.3 3 ( - f) - 5/2,

Maximum values of higher coefficients:

d, ( {) = .OOO .

I bl ({) 1 = .OO3, J u ~ ({) I = .0008, Id2 ({) I = .001

Icl({)I=.008 ({<lo), C1({)--.003{* as {++OD.

9.4. Polynomial Approximations

9.4.1 - 31x13

J~(x) = 1-2.24999 97(~/3)'+ 1.26561 08(~/3)~ -.31638 66(~/3)~+.04444 79(~/3)'

-.00394 44(~/3)'~+.00021 0 0 ( ~ / 3 ) ~ ~ + ~

lt1<5X 10-8

9.4.2 0<x13

Yo(x) = (2/~) ln($x)J,(x) + .36746 691 +.60559 366(~/3)'- .74350 384(~/3)~

+ .25300 1 17 (2/3) '- .0426 1 2 14 (~/3) + .00427 916(~/3)"- .00024 846 (~/3) 12+ t

Itl< 1.4X lo-*

9.4.3 31x< 03

Jo(x) =x-tfo cos e, Yo(x) =x-+j, sin e, fo=.79788 456- .OOOOO 077(3/~) - .00552 740(3/~)'

-.00009 512(3/~)'+ .00137 237(3/~)'

- .00072 805(3/~)~+ .00014 476(3/~)*+t

[el< 1.6X lo-* 2 Equations 9.4.1 to 9.4.6 and 9.8.1 to 9.8.8 are taken

from E. E. Allen, Analytical approximations, Math. Tables Aids Comp. 8, 240-241 (1954), and Polynomial approxi- mations to some modified Bessel functions, Math. Tables Aids Comp. 10, 162-164 (1956) (with permission). They were checked at the National Physical Laboratory by systematic tabulation; new bounds for the errors, e, given here were obtained as a result.

Page 16: Bessel functionsofintegerorder1

370 BESSEL FUNCTIONS OF INTEGER ORDER

e0=Z- .78539 816- .04166 397(3/4 -.00003 954(3/~)~+ .00262 573(3/~)~

-.00054 125(3/~)’- .00029 333(3/~)‘ +.00013 558(3/x)’+a

l€1<7X 10-8

9.4.4 - 35x53

z-’ J1 (z) =*- A6249 985 ( ~ / 3 ) ~ + .2 1093 573 (~/3)’ -.03954 289(~/3)’+ .00443 319(~/3)’

- .00031 761 (~/3)”+ .00001 109(~/3)’~+€

lt1<1.3X10-8

9.4.5 O<x53

zYl(s)=(2/?r)xln(~s)Jl(z)-.63661 98 + .22120 91 (~/3)~+2.16827 09(x/3)’ - 1.31648 27(~/3)’+ .31239 51 (2/3)’

- .04009 76(~/3)”+ .00278 73(Z/3)12+c

/al<l.lXlO-’

9.4.6 3 Is<

J1(z)=s-+jl COS e,, Yl(x)=x-+jl sin e, fi=.79788 456+.00000 156(3/~)+.01659 667(3/~)~

+.00017 105(3/~)~-.00249 511(3/~)’ +.00113 653(3/~)~- .00020 033(3/~)’+~

IC1<4X 10-8

e1=~-2.356i9 449 + .12499 612 (3/4 + .00005 650(3/~)’- .00637 879(3/~)~ + .00074 348(3/~)‘+.00079 824(3/x)‘

-.00029 166(3/~)’++t

lt1<9X10-8

For expansions of Jo(s), Yo(s>, Jl(z), and Yl(x) in series of Chebyshev polynomials for the ranges 05s<S and 0<8/z5l, see t9.371.

9.5. Zeros

Real Zeros

When Y is real, the functions J,(z), Jl(z), Y,(z) and Y:(z) each have an infinite number -of real zeros, all of which are simple with the possible exception of z=O. For non-negative Y the 6th positive zeros of these functions are denoted by

- *t J,.,~, J,.,~, yv . a and Y:,a respectively, except that z=O is counted as the h t zero of JA(z). Since Ji(z)=-Jl(z), it follows that

*I . 9.5.1 jL,i=O, ~ o . s= j i . s - i (s=2, 3, . .)

The zeros interlace according to the inequalities

9.5.2 ~.,l<~.+l,l<j.,Z<j~+,,Z<jU,3< * * .

Y*.l<Y~+l.l<Y..2<Yv+l.2<Yu.3< * - &j:, I<Y., I<Y:, ~<j., ,<A, 2

<Y., Z<Y:, 2<jp, 2< j;, 3< . . .

The positive zeros of any two real distinct cylinder functions of the same order are interlaced, as are the positive zeros of any real cylinder function %‘,(z), defined as in 9.1.27, and the contiguous function V,+,(Z).

9.5.3 Vp(z) = J,(z) cos(d) + Y,(z) sin(?rt)

where t is a parameter, then

If pv is a zero of the cylinder function

9.5.4 u:(P,)=u.-l(P.) = - U . + , ( P . >

If u. is a zero of W;(z) then

The parameter t may be regarded as a continuous variable and pr, u, as functions p . ( t ) , u,(t) of t. If these functions are fixed by

9.5.6 p,(O)=O, u.(o)=j;, 1

then

9.5.7

j”,*=P,(s), Y.,I=Pu(s-3) (s=l,2, . .I

9.5.8

ji,a=gv(s-1), y;.a=Cv(s-$) (s=l, 2, *)

Infinite Products

Page 17: Bessel functionsofintegerorder1

BESSEL FUNCTIONS OF INTEGER ORDER

McMahon's Expansions for Large Zeros

371

When v is fixed, s>>v and p=45

. . . - 64(p-l) (69494-1 53855p2+15 85743~-62 77237) - 105(8b)7

where P=(s+$v-4)a forjv,s, P=(s+$v-$)r for yI,*. asymptotic expansion of pY(t) for large t.

With p=(t+4v-t)al the right of 9.5.12 is the

. . . - 64(6949p4+2 96492~~- 12 48002p2+74 14380~-58 53627) - 105(88')'

where S'=(s+$v-q)a for jL.81 B'=(s+#v--))a for yl,,, B'=(t+$v+t)a for uI(t). For higher terms in 9.5.12 and 9.5.13 see [9.4] or [9.40].

Asymptotic Expansions of Zeros and Associated Values for Large Orders

9.5.14 jy,l - v+ 1.85575 71 v1l3+ 1.033 15 OV-"~

-.oo397v-'-.0908v-~/3+.043v-7/3+ . . .

9.5.15 yv, 1-v+.93157 68vlf3+.26O35 lv-li3

9.5.16 j:.,-v+ 30861 65~'/~+.07249 Ov-lf3

9.5.17

+ .01198v-'- .0060~-'~~- .001~-"~+ . . .

- .05097~-'+ .0094~-"~+ . . .

y:, 1.~~+1.82109 80~'/~+.94000 7v-l" - .05808v-'- .0540~-'~~+ . . .

9.5.18 JL(jv,l) ---1.11310 28~-~/~/(1+1.48460 6 ~ - ~ / ~

+ .43294V-4/3-.1943v-2+ .019v-8/3+ . . . )

9.5.19 Y:(yv, 1) m.95554 86~-~/~/(1+ .74526 lv-2/3

+.10910v-'~3-.0185v-2-.003v-*/~+ . . . )

9.5.20 JP(jL,1) m.67488 51~-'/~(1--.16172 3 ~ - ~ / ~

+ .02918~-~'~- .0068~-~+ . . . ) 9.5.21 Y&:, J m.57319 40~-"~(1- .36422 O V - ~ / ~

+.09077~-*~+.0237v-~+ . . . )

Corresponding expansions for s=2, 3 are given in [9.40]. These expansions become progressively weaker as s increases; those which follow do not suffer from this defect.

Uniform Asymptotic Expansions of Zeros and Associated Values for Large Orders

9.5.22 j,.,-vz(r)+C OD f k ( r > with {= ~ - ~ / ~ a , k= l

9.5.23

with {=~ - ~ / ~ a ,

(D

9.5.24 j;,,-vz({)+C With {=~ - ~ / ~ a :

9.5.25 b-1 P-'

where a,, a: are the sth negative zeros of Ai@), Ai'(z) (see 10.4), z=z(T) is the inverse function defined implicitly by 9.3.39, and

9.5.26 h(O=I4t/(1--z2)It jl(r) =Mr)Ih(r) 12bo(l) m(n=3r-'z(r>{h(r)12co(r)

where bo({), co({) appear in 9.3.42 and 9.3.%. Tables of the leading coefficients follow. More ex- tensive tables are given in [9.40].

The expansions of yv. a, YXyv, a), y:. I and Y.(Y:. J corresponding to 9.5.22 to 9.5.25 are obtained by changing the symbols j, J, Ai, Ai', a, and a: to y, Y, -Bi, -B?, b, and b: respectively.

Page 18: Bessel functionsofintegerorder1

372

h (i-)

1. 25992

BESSEL FUNCTIONS OF INTEQER ORDER

fl (i-)

0. 0143 -. ~ _ . .

1.22076 1. 18337 1. 14780 1. 11409 1.08220

-. 0142 .0139 .0135 .0131

0.0126

0. 40 .35 .30 .25 .20

1.528915 1. 541532 1. 551741 1.559490 1.564907

0. 15 . 10 .05 . 00

1.568285 1.570048 1. 570703 1.570796

-i-

1.000000 1. 166284 1.347557 1.543615

-0.007 -. 005 -. 004 -. 003 -. 003

-0.002

-0. 1260 -. 1335 -. 1399 -. 1453 -. 1498

-0. 1533

-0.010 -. 010 -. 009 -. 009 -. 008

-0. 008

0. 000 .002 .004 .005 .006

0.006

0. 0 0. 2 0. 4 0. 6 0. 8 1. 0

-r - 1. 0 1. 2 1. 4 1. 6 1. 8

2. 0 2. 2 2. 4 2. 6 2. 8

3. 0 3. 2 3. 4 3. 6 3. 8

4.0 4.2 4.4 4.6 4.8

5. 0 5. 2 5. 4 5. 6 5. 8

6. 0 6. 2 6. 4 6. 6 6. 8

7. 0

1.754187 1.978963

1.978963 2. 217607 2. 469770 2. 735103

0.0120 .0121 .0115 . 0110 .0105

0.0100 .0095 .0091 .0086 .0082

0.0078 .0075 .0071 .0068 .0065

0.0062 .0060 .0057 .0055 .0052

0.0050 .0048 .0047 .0045 .0043

0.0042 .0040 .0039 .0037 .0036

0.0035

-0.002 -. 002 -. 001 -. 001 -. 001

-0.001 -0.001

-0.008 -. 004 -. 002 -. 001 -. 001

-0.001

0.006 .004 .003 .002 .002

0.001 .001 . 001 .001

0.001

1.08220 1. 05208 1.02367 0.99687 .97159

0.94775 . 92524 .90397 .a8387 . 86484

0.84681 .a2972 . 81348 . 79806 .78338

0. 76939 .75605 . 74332 . 73115 .71951

0. 70836 .69768 . 68742 . 67758 . 66811

0. 65901 .65024 .64180 .63366 .62580

0.61821

-0. 1533 -. 1301 -. 1130 -. 0998 -. 0893 3.013256

3.303889 3. 606673 3. 921292 4. 247441 4.584833

4. 933192

-0.0807 I -. 0734 -. 0673 -. 0619 -. 0573

- I -0.0533 -. 0497 -. 0464 -. 0436 -. 0410

-0.0386 -. 0365 -. 0345 -. 0328 -. 0311

-0.0296 -. 0282 -. 0270 -. 0258 -. 0246

5. 292257 5.661780 6.041525 6. 431269

6. 830800 7. 239917 7. 658427 8.086150 8. 522912

8.968548 9.422900 9.885820

10.357162 10.836791

11.324575 11. 820388

-0.0236 -. 0227 -. 0218 12. 324111

12. 835627 13.354826

13.881601

-. 0209 -. 0201

-0.0194

Complex Zeros of J,(s)

When v> -1 the zeros of J,(z) are all real. If v<-1 and v is not an integer the number of com- plex zeros of J,(z) is twice the integer part of (-v); if the integer part of (-v) is odd two of these zeros lie on the imaginary axis.

If v20, all zeros of JL(z) are real.

( --f)W)

1.62026 1.65351 1. 68067 1. 70146 1.71607

1.72523 1.73002 1.73180 1. 73205

81(3)

-0.0224 -. 0158 -. 0104 -. 0062 -. 0033

-0.0014 -. 0004 -. 0001 -. 0000

0.0040 .0029 .0020 . 0012 .0006

0.0003 . 0001 .moo .woo

Complex &roo of Y,(r)

When vis real the pattern of the complex zeros of P,(z) and Yv(z) depends on the non-integer part of v. Attention is confined here to the case u=n, a positive integer or zero.

Page 19: Bessel functionsofintegerorder1

a=m= . 6 6 2 7 4 . . .

b = + J m I n 2=.19146 . . . and b=1.19968 . . . is the positive root of coth t =t. There are n zeros near each of these curves. Asymptotic expansions of these zeros for large n

I

FIGURE 9.6. Zeros ofHi’)(z) and Hi”’(z) . . . larg zl<?r.

The asymptote Of the solitary infinite curve is given bY

Y~=-+In2=-.34657 . . .

Page 20: Bessel functionsofintegerorder1
Page 21: Bessel functionsofintegerorder1

BESSEL FUNCTIONS

I:

FIGURE 9.8. e-zlo(z),e-zIl(~),eZKO(;C) and e"Kl(z).

FIGURE 9.9. 1,(5) and K,(5).

Relations Between Solutions

9.6.2 K( z )=h I-,(z) sin -I,(z) (y.)

The right of this equation is replaced by its limiting value if v is an integer or zero.

9.6.3 I,(z) =e-+prfJ,(zetrf) (-r<arg 2<34

(3*<arg z 54 I,(z) =e3fl'/2J,(=-3"/2 1 9.6.4

K,(z)=)riet"'H~')(zet"') (-r<arg z<$r) K,(z) = - 3rie-+*f HP) (ze-+") (- &<arg z <r)

OF INTEGER ORDER 375

9.6.5 Y,(zeW) =et(,+l)riI ,( z 1 - (2/~)e-+*~K,(z)

(-*<a% z<h)

9.6.6 I-,(z)=l,(~), K-,(z)=K,(z)

Most of the properties of modified Beasel functions can be deduced immediately from those of ordinary Bessel functions by application of these relations.

Limiting Forms for Small Arguments

When v is fked and z+O

9.6.7

Iv(+(iz)yr(v+i) (vz -1, -2, . . .)

9.6.8 Ko(z)--ln z

9.6.9 K,(z)-+r (V)(~Z)- ' ( g v>o )

Ascending Series

o (42")" 1,(2)=(42)v 2 myv+k+i)

Kn(z>=&(34-" go k! (-322))"

9.6.10

9.6.11 n-1 (n-k-l)!

+ (-In+1 In (34In(~) (tz")" +(->"3(3d" 2 INC+l)+W+k+l) 1 k!(n+k)!

k-0

where +(n) is given by 6.3.2.

4z2 (+z">" (tz2)3+*. . 9-6-12 Io(~)=l+-+-+- (1!)2 (2!)2 (3!)2

9.6.13 4 z2 Ko(z)= - {h (3 Z)+YI~O(Z) +m

(4z">" (tz"3+* +(1+3) (,!),+(1+3++) (3!)2 a -

Wronskians 9.6.14 W{ I&), I&) 1 =I,(z)l-~,+l~(z)-I,+l(z)I-,(z)

= -2 sin (vr)/(~z) 9.6.13 W{ K,(z) , I,( z) } =I&) K,+l(z) + Iv+l (2) ZJ,z) = l/z

Page 22: Bessel functionsofintegerorder1

376 BESSEL FUNCTIONS OF INTEGER ORDER

Integral Representations 9.6.16

Io(z)=’S‘ ‘ A 0

9.6.17 K~(z)=-- {?+In (22 sin2 e)}&

9.6.18

0

Ko(z) =l cos (z sinh t)dt=lm c* dt

(X>O) 9.6.22

K.(z)=sec (3m) cos (z sinh t) cosh (vt)dt

=csc ( 3 ~ ) l- sin (z sinh t) sinh (vt)dt

l- (194 <11 z>O)

9.6.23

9.6.24 K.(z)= cosh (ut)& (larg 21 <h)

9.6.25 J O

9.6.27

9.6.28

%”, denotes I”, eurfKv or any linear combination of these functions, the coefficients in which are independent of z and v.

I;(Z) = rl (z), K; (2) = - K~ (z)

Formulas for Derivatives

Analytic Continuation

9.6.30 Iu(zemrf) =em”’‘Iu(z) (m an integer)

9.6.31

Kv( t) = e-mmf Kv(z)--?ri sin (mvn) csc (v?r)I,(z) (m an integer)

9.6.32 I.(Z)=I.(z), K,.(B)=K,(z) (V real) - -

Generating Function and Associated Series

9.6.33 2 tkIk(z) (t#O) k=-m

m

9.6.34 ez cOse=Io(z) +2 C Ik(z) cos(k0) k-1

+2 2 k=l ( - ) ~ ~ ~ ( z ) cOs(2ke)

9.6.36 l=Io(~)-212(~)+214(~)-21~(~)+ . . .

9.6.37 ez=Io(z)+211(2)+212(2)+213(2)+ . . ,

9.6.38 e-z=Io(z)-~11(2)+212(2)-~13(2)+ . .

9.6.39 cosh ~=I~(z)+21~(~)+21,(~) +216(2)+ . . .

9.6.40 sinh 2=211(2)+213(z)+21~(2)+ . . . *See page 11.

Page 23: Bessel functionsofintegerorder1

BESSEL FUNCTIONS OF INTEGER ORDER 377 Other Werential Equations

The quantity X2 in equations 9.1.49 to 9.1.54 and 9.1.56 can be replaced by -A2 if at the same time the symbol W in the given solutions is replaced by 3.

9.6.41 zzw" + z( 1 f 2 2) w ' + ( f 2- S)w=O, w =e~2f2",( z)

Differential equations for products may be obtained from 9.1.57 to 9.1.59 by replacing z by iZ.

Derivatives With Reepect to Order 9.6.42

9.6.43

9.6.46

9.6.46

Expreesions in Terms of Hypergeometric Functions

9.6.47

9.6.48

OF^ is the generalized hypergeometric function. For M(a, b, z), Mo,,(z) and Wo,,(z) see chapter 13.)

Connection With Legendre Functions

If LL and z are fixed, Wz>O, and v+w through real positive values

9-6-49 lim{vre

9.6.50 E m { v-pe-p"

For the definition of P;" and Qf, see chapter 8.

Multiplication Theorems 9.6.51

Zeros

Properties of the zeros of I,(z) and K,(z) may be deduced from those of J,(z) and Hf)(z) respec- tively, by application of the transformations 9.6.3 and 9.6.4.

For example, if v is real the zeros of IJz) are all complex unlese -2k<v<- (2k- 1) for some posi- tive integer k, in which event I,(z) has two real zeros.

The approximate distribution of the zeros of K,,(z) in the region -#r<arg z s a r i s obtainedon rotating Figure 9.6 through an angle -3r so that the cut lies along the poaitive imaginary axis. The zeros in the region -$a <arg z 53% are their conjugates. K,,(z) has no zeros in the region larg zI <$a; this result remains true when n is replaced by any real number v.

9.7. Asymptotic Expansions

Asymptotic Expansions for Large Arguments

When v is fixed, IzJ is large and r=49

9.7.1

Page 24: Bessel functionsofintegerorder1

BESSEL FUNCTIONS OF INTEGER ORDER 378 9.7.2

9.7.3 \

- G-1)G-9)G+35)+ . . .} (larg 21 <b) 3! (82)' 9.7.4

+ (r-1)G-9)G+35)+ 3 ! ( 8~ ) ~ . . .} (Iarg Zl<+r)

The general terms in the last two expansions can be written down by inspection of 9.2.15 and 9.2.16.

If Y is real and non-negative and z is positive the remainder after k terms in the expansion 9.7.2 does not exceed the (k+l)th term in absolute value and is of the same sign, provided that k l v - - 3 .

9.7.5

( lag Z K b ) The general terms can be written down by inspection of 9.2.28 and 9.2.30.

Uniform A~wptot ie Expandons for Large Orders

9.7.8

9.7.10

When v++ m , these expansions hold uniformly with respect to z in the sector larg z1S&r--t, where e is an arbitrary positive number. Here

and Uk(t), q(t) are given by 9.3.9, 9.3.10, 9.3.13 and 9.3.14. See [9.38] for tables of q, uk(t), vr(t), and also for bounds on the remainder terms in 9.7.7 to 9.7.10.

9.8. Polynomial Approximations

In equations 9.8.kto 9.8.4, t=x/3.75.

9.8.1 -3.75 5 s 53.75

Io(x)=1+3.51562 29t2+3.0899424t4+1.20674 92t"

I~1<1.6XlO-~ + .26597 3294- .03607 68t10+ .00458 13t"+c

9.8.2, 3.75 Is<- x~e-zIo(x) = .39894 228 f .01328 592t-I

+.00225 319t-2-.00157 565t" +.00916 281t-'-.02057 706P +.02635 537t-'-.01647 633t-'

+ .00392 377tT- a la]< 1.9 x lo-'

9.8.3 -3.75 5x53.75 ~-'I1(~)=3+.87890 594ta+.51498 869t'

+ .15084 934t" + .02658 733@ +.00301 532t1°+.00032 411t12+a

l4<8 X 10-e

9.8.4 3.75 I x <m de-'II(x) = ,39894 228 - .03988 024t-'

-.00362 018t-2+.00163 801t-' --.01031 555t-'+.02282 967t-' - .02895 312t-'+ .01787 654t-'

- .00420 059t-'+t la1<2.2X 10-7

4 See footnote 2, aection 9.4.

Page 25: Bessel functionsofintegerorder1

BESSEL FUNCTIONS OF INTEGER ORDER 379 9.8.5 O<X12

&(s)=--ln (~/2)10(2)-.57721 566 +.42278 420(~/2)~+ .23069 756(x/2I4

. +.03488 590(~/2)'+ .OO262 698(~/2)' +.OOOlO 750(x/2)10+.00000 740(z/2)12$~

It1 <1 x 10-8 9.8.6 2Ix<..

z*ez&(z)= 1.25331 414-.07832 358(2/z) +.02189 568(2/~)*-.01062 446(2/~)' +.00587 872(2/~)~- .00251 540(2/~)~

+.00053 208(2/z)'+e IcI<1.9xlO-'

9.8.7 0<212

ZKl(Z)=z I n (2/2)11(~)+1+.15443 144(~/2)~ - .67278 579(~/2)~--. 18156 897(~/2)' - .019 19 402 (312)'- .OO 1 10 404 (~/2) lo

-.00004 686(z/2)12+e [e[ <8X lo-"

9.8.8 2 sx< OJ

dezK1(2)=1.25331 414+.23498 619(2/z) - .03655 620(2/~)'+ .OX04 268(2/~)~ -.00780 353(2/~)'+ .00325 614(2/~)~

- 40068 245(2/X)'+a lt1<2.2x10-7

For expansions of l0(z), K&), Il(z), and Kl(z) in series of Chebyshev polynomials for the ranges Os258 and 018/z11, see [9.37].

Kelvin Functions

9.9. Definitions and Properties

In this and the following section Y is real, z is real and non-negative, and n is again a positive integer or zero.

Diiferential Equations 9.9.3

x2wtf +xwt- (iStl+va)w=O, w=ber, z+i bei, z, ber-, z+i bei-, 2,

ker-, z+i kei-, z ker, z+i kei, z, 9.9.4 ~cwt8+2223tv- (1 +22) ( 5 ~w~~ - xw~ )

+ ( v4- 4 ~ *+ x~)w= 0 , w=ber*, x, bei*, z, ker*, z, kei*, x

Relations Between Solutions 9.9.5 ber-, z=cos(vr) ber, z+sin(vx) bei, z

+ (2/r) sin(ur) ker, z

bei-, z= -sin(~r) ber, z+cos(vr) bei, z + (2/r) sin(vr) kei, z

9.9.6 ker-. X=COS(VT) ker, z-sin(vx) kei, r ke i , z=sin(vx) ker, z+cos(vr) kei, z

9.9.7 ber-, a= (-)" ber, 1, bei-, x= (-)" bei, z

9.9.8 ker-, x= (-)" ker, r, kei-, z= (-)" kei, z

Ascending Seriee

9.9.9

9.9.10 (4g)2 I (4.")' . . . ber z=l-- (2!)2 (4!)2

Page 26: Bessel functionsofintegerorder1

380 BESSEL FUNCTIONS OF INTEGER ORDER

(n-k- l)! k! (t$)k-ln (3x) bei, x-4.. ber, x

where #(n) is given by 6.3.2.

9.9.12 ker x=-ln (42) ber x+tx bei x

kei x= --In ($2) bei x-tr ber x

Functions of Negative Argument

In general Kelvin functions have a branch point at z=O and individual functions with argu- ments zefri are complex. The branch point is absent however in the case of ber, and bei, when v is an integer, and

9.9.13

ber,(-z) = (-)” ber, z, bei,(-x) = (-)* bei, z

Recurrenee Relations

9.9.14

v 1 j :- ;jv=- Vv+l+gu+l)

f:+,f,=--- Cf,-,+g,-,>

Jz V 1

Jz where

9.9.15 f,=ber, XI j,=bei, x ‘1 gv=bei, x J j,=ker, x

g,=kei, x

g,=-ber, x J f,=kei, x

g,=-ker, x

9.9.16 ber‘ x=ber, x+beil z

bei’ x=-ber, x+bei, x 9.9.17

8 ker’ x=kerl x+kei, x

8 kei’ x=-kerl x+kei, x

Recurrence Relations for Goas-Products If

9.9.18 p.=bee x+beil x q,=ber, x bei: x-ber: x bei. z r,=ber, x ber: z+bei, x bei: x s.=ber? x+bei? x

then

9.9.19

Y

~;+1=--2p,+r,=--q,-,+2r,

and

9.9.20 pP&=8+d,

The same relations hold with ber, bei replaced throughout by ker, kei, respectively.

Indehite Integrals

In the following j,, g, are any one of the pairs given by equations 9.9.15 and jf, gf are either the same pair or any other pair.

9.9.21

9.9.22

Page 27: Bessel functionsofintegerorder1

BESSEL FTJNCTIONS OF INTEGER ORDER 381

5. 84892 7. 23883 11. 67396 16. 11356 20. 55463

9.9.24 1 J- x (f”g: +gy3CZ)dx=4 x2 (2fYg: - f v - 19*s+1

J- x (3-r g3 dx= z(fvg:-flg”)

-fy+1g2-1+2g.f*s-gv-,f~+1-g.+1f*s-1) 9.9.25

= - < z / a (f If ”+ 1 + g&+ 1 -fYgr+ 1. +f Y + 1 gv)

9.9.26 1 J zf ,gPdx=~ X V f 4 p - f P.-lg”+l-j”+lgr-l)

J X V : - sZ)dx=z 9 (f”y-fv- 1f.+1- gf + Y Y - 19.+1)

9.9.27 1

Ascending Series for Cross-Producta 9.9.28 be s x+bei: x=

5. 02622 9. 45541 13. 89349 18.33398 22. 77544

9.9.29

ber, x bei: x-ber: x bei, x

6. 03871 10. 51364 14. 96844

9.9.30

ber, x ber: x+bei, x bei: x

3. 77320 8. 28099 12. 74215

9.9.31

bedz x+beiL2 x

Expansions in Series of Bessel Functions

9.9.32

V + d 4 m e ( a ~ + k ) r i 1 4 ~ J

2tk k! ber, x+i bei, x = C k =O

9.9.33

Zeros of Functions of Order Zero 6 ~ I berz I bei x I kerz I keix

1st zero 2nd zero 3rd zero 4th zero 5th zero

1st zero 2nd zero 3rd zero 4th zero 5th zero

ber’x I bei‘x

19. 41758 17. 19343 23. 86430 21. 64114

1. 71854 6. 12728 10. 56294 15. 00269 19. 44381

ker‘ x

2. 66584 7. 17212 11. 63218 16. 08312 20. 53068

-

3.91467 8. 34422 12. 78256 17. 22314 21. 66464

kei’ z

4.93181 9. 40405 13.85827 18. 30717 22.75379

9.10. Asymptotic Expansions Asymptotic Expansions for Large Arguments

When Y is fixed and x is large

9.10.1

ber, x=- {f,(x) cos a+gv(z) sina} &d2

42Tx 1 -- {sin ( 2 4 ker, x+cos (2vn) kei, x} n-

9.10.2

bei, x = r t f , ( x ) sin a-g,(x) cos a} e‘lJ2 ,

*X

1

n- +- {cos ( 2 4 ker, x-sin ( 2 4 kei, x}

9.10.3 ker, x=dme - z l d 2 { f v ( - x ) cos B-g,(-x) sin

9.10.4 kei, x=dme-z/d2( - j , ( -x) sinp-g.(-x) COS^} where

9.10.5

a= (z/fi)+($v- g>n-, 8= (-6/Jz>+(Bv+t)n=a+4n-

and, with 42 denoted by p,

9.10.6

f.(ztx)

cos(?) ( -l)(p-9). . .{p-(2k--l)Z] -l+&T)k k-1 k! (8s)’ . .

6 From British Association for the Advancement of Science, Annual Report (J. R. Airey), 254 (1927) with permissioL. This reference also gives 5-decimal values of the next five zeros of each function.

Page 28: Bessel functionsofintegerorder1

382 BESSEL FUNCTIONS

9.10.7

df 4 sin ($) ( - I ) (p -g) . . .{p-(2k-I)*}

k! (82) k

The terms" in ker,x and kei,x in equations 9.10.1 and 9.10.2 are asymptotically negligible compared with the other terms, but their inclusion in numeri- cal calculations yields improved accuracy.

The corresponding series for ber; x, b ei: x, ker: x and kei: x can be derived from 9.2.11 and 9.2.13 with ~ = x e ~ ~ ' l ~ ; the extra terms in the expansions of ber: x and bei; x are respectively

-(1/~) {sin(2vlr)ker; s+cos(2vr)kei: 2)

( I/T) {cos ( 2 ~ 4 ker: s-sin (2vlr) kei: 2) .

Modulus and Phase

-2 e)k Cc k-1

and

9.10.8 M,=,/(be~z+bei:x), @,=arctan (bei,x/ber,r)

9.10.9 ber,x=M, cos e,, bei,x=M, sin 8,

9.10.10 M-,=M,, e-,=e,--nT

9.10.11 ber: jC=#M,+, cos (O,+l-i+$ M,-l cos (L1-&r)

= (y/~)M. COS e,+M,, COS (eV+,-id = - (v/~)M, COS e,-M,-, COS (e,-,-+T)

9.10.12 bei: x= #M,+, sin (e,+, - 4.) - #M,-l sin (e,-l - tr)

=(~/x)M,sin e,+&, sin (e,,,-4T) = - (v/$)M,sin e,-M,-, sin (e,-,-+r)

9.10.13 ber' z=Ml cos (O1-fr),

9.10.14

bei' x=Ml sin (el-i?r)

M;= (V/Z)M,+M,+, COS (e,,-e,-ir> = - ( v / ~ ) ~ , - ~ , - l COS (e,-l-e,-+T)

e:= (M,+JM,) sin (e,+,-e.-44 9.10.15

= - (M,-l/M,) sin (e,-l-e,-tT)

8 The coefficients of these terms given in [9.17] are in- correct. The present results are due to Mr. G. F. Miller.

OF INTEGER ORDER

9.10.16 M;=Ml COS (el-eo-tlr) e;=(Ml/Mo) sin (el-eo-+r)

9.10.17

d(rwe;)/d;c=2w, ~ ~ ; ' + r ~ ; - - ~ , = ~ ~ d ; ~

9.10.18

N,=d(kee3 +kei:x), $,=arctan (kei,z/ker,x)

9.10.19 ker,s=N, cos $,, kei,z=N, sin 4,

FIGURE 9 . 1 1 . In Mo(x), eo(x), I n No(x) an& 40(x).

Equations 9.10.11 to 9.10.17 hold with the symbols b, M, e replaced throughout by k, N, 4, respectively. In place of 9.10.10

9.10.20 N_,=N,, &,=$.+vr

Page 29: Bessel functionsofintegerorder1

BESSEL FDNCTIONS OF INTEGER ORDER 383 Asymptotic Expansions of Modulus and P h e

When Y is fixed, x is large and p=49

9.10.21 er/@ p-1 1 ( ~ - 1 ) ~ 1 M,=- {I-- - +- - fix 842 x 256 9

- (p- 1) (p2+ 14p-399) 1 614442

9.10.22 X p-1 1 (p-l)(p-25) - 1

In M.=a-f In (27rx)-- -- 842 x 38442 23

9.10.23

9.10.24

( I)(p2+14p-399) 1 + p- 614442 2 3 -+o ($)I

9.10.25

9.10.26

Asymptotic Expansions of Cross-Products

If x is large

9.10.27

ber2 x+ bei2

. . .) 33 1 1797 1 25642 z8 8192 2' -- ---

9.10.28 elda 1 1 1 ber x bei' x-ber' x bei x-- -+- - 2?rx (42 8 x

. . .) +- 9 1 3 9 1 -+- -+- 7 5 1 6442x2 51223 8192422'

9.10.29 #da 1 3 1 ber x ber' x+bei x bei' x-- --- - 2 r ~ (42 8 x

15 1 45 1 315 1 6442~ ' 5122 819242 x4 -- --- -+--+ . .

9.10.30 bef2 x+bei'2 x - c 2 (I-- 3 1 -+- 9 1 -

~ T X 4d2x 64 X'

75 1 2475 1 +=2 -+--+ 9 8192 x4 . .

9.10.31 'K 1 1 1 1 22 ( 4422'642

ker2 x+kei2 x--e-1d2 1--

. . .) 33 1 1797 1 + +----- 256429 8192~'

9.10.32 T ker x kei' x-ker' x kei x--- 22 e-zda

9 1 3 9 1 75 1 64429 5129 8192422' +- --- -+-----+ . .

9.10.33

ker x ker' x+ kei x kei' z - - - 15 1 45 1 315 1

6442~ ' 5122 8 1 9 2 4 2 ~ ~ -- -+- -+- -+ . .

9.10.34

75 1 2475 1 2561/221 8192x4 -- -+- -+ . . .)

Asymptotic Expandom of h r g e zero8

Let 9.10.35

where p=4v2.

9.10.36

Zeros of ber, z-&(S-f(S)}, 6=(8--v-#)r

Then if R is a large positive integer

Zeros of bei. x-dz{ S-f(S)}, 6= (8-3Y+*)T

Zeros of ker. x-a{a+j(-S)}, S=(~-fv-Q)r

Zeros of kei. x-a{S+j(-S)}, S=(~-~Y-+)T

Page 30: Bessel functionsofintegerorder1

384 BESSEL FUNCTIONS OF INTEGER ORDER

For v=O these expressions give the sth zero of each function; for other values of v the zeros represented may not be the sth.

Uniform Asymptotic Expansions for Large Orders

When Y is large and positive

9.10.37

berJvx) +i bei,(vx) -

9.10.38 ker, (vx)+i kei, (vx)

9.10.39 ber: (vx)+i bei: (YX)

9.10.44) ker: (vx)+i kei: (vx)

where

9.10.41 €=&s and uk(t), cr(t) are given by 9.3.9 and 9.3.13. fractional powers take their principal values.

All

9.11. Polynomial Approximations

9.11.1 -8<x<S ber x= 1 - 64(2/8) * + 11 3.77777 774(r/8)'

- 32.36345 652 (~/8) "+2.6419 1 397 (~/8) l6

-.08349 609(~/8)~+.00122 552(~/8)" - .OOOOO 901 (~/8)"+t

Icl<l x 10-9 9.11.2 -85x18 bei Z= 16(x/8)'-113.77777 774(~/8)~

+ 72 31777 742 (218) lo- 10.56765 779 (~/8) l4

+ .52 185 6 15(~/8)"- .O 1 103 667 (~18) a2

+ .00011 346(~/8)''+6 lel<6X10-'

9.11.3 O<x<8

ker x= -In (tz) ber z+~'K bei 2-37721 566 -59.05819 744(~/8)~+171.36272 133(~/8)' -60.60977 451 (2/8)"+5.65539 121 (2/8)16 -.i9636 347(~/8)20+.00309 e99(~/8)*4

Itl<lX10-'

-.00002 458(~/8)''+e

9.11.4 O<x<8

kei x=-ln($x)bei x-tr ber s+6.76454 936f$$3)2 -142.91827 687(%/8)'+ 124.23569 650(~/8)'O -21.30060 904(~/8)'~+ 1.17509 064(~/8) -.02695 875(~/8)'~ +.00029 532(~/8)*'+t

I€l<3X 10-9

9.11.5 -8<~58

ber' x=z[ -4(d8)'+14.22222 222(~/8)~ -6.06814 810(~/8)"+ .66047 849(~/8) I'

-.02609 253(~/8)''+.00045 957 (~/8 )~ -.OOOOO 394(~/8)'~]+a

lt1<2.1 x10-E

9.11.6 -8<2<8

bei' z=z[)- 10.66666 666(x/8>' +11.37777 772(~/8)'-2.31167 514(~/8)" +.14677 204(~/8)"- .00379 386(~/8)*O

+ .00004 609(s/8) *'I + t

lt1<7x10-'

9.11.7 O<x<8

ker' x= --In ($2) ber' x-z-l ber X+$T be? z +x[ - 3.69 1 13 734 (~/8)'+2 1.42034 0 17 (~/8)' - 11.36433 272 (48) lo+ 1.41384 780(2/8) l4

- .06 136 358 ( d 8 ) "+ .OO 1 16 137 (~/8) "

- .OOOO 1 075 (2/8) "1 + t

lc1<8X lo-'

Page 31: Bessel functionsofintegerorder1

BESSEL FU.”IONS OF INTEGER ORDER 385 9.11.8 O<xl8

kei’ x= -ln (32) bei’ 2 - P bei x - f ~ ber’ x - 4-4.21 139 217 - 13.39858 846(~/8)~ + 19.41 182 758(~/8)”-4.65950 823(~/8)’* f.33049 424[~/8)’”- .00926 7 0 7 ( ~ / 8 ) ~

+ .OOO 1 1 997 (x/8) +e

le1 <7 x 10-8

9.11.9 85x<-

ker x+i kei x=j(x)(l+tl)

9.11.10 81x< w

i her x+i bei x-- (ker x+i kei x)=g(x)(1+s2) T

lC1<3X 10-7

Numerical

I 9.12. Use and Extension of the Tablee

Examplel. To evaluate Jn(1.55), n=O, 1, 2, . ., each to 5 decimals. The rdcurrence relation

Jm-1 (z) + Js+l(~) = (2n/x)Js(x) I can be u s 4 to compute Jo(x), J1(x), J&), . . ., successively provided that n<x, otherwise severe accumulation of rounding errors will occur. Since, however, Jn@) is a decreasing function of n when n>x, recurrence can always be carried out in the direction of decreasing n.

Inspection of Table 9.2 shows that Jn(1.55) vanishes to 5 decimals when n>7. Taking arbi- trary values zero for Jo and unity for J8, we compu te by recurrence the entries in the second column of the following table, rounding off to the nearest integer at each step.

where 9.11.11 e($) = (.ooooo 00---.39269 91i)

+(.01104 86-.01104 85i)(8/~) (.OOOOO 00- .00097 6%) (8/~)’

+ (- .OOOO9 06- .00009 O l i ) ( 8 / ~ ) ~

+ (- .00002 52 + .OOOOO OOi) (S/X)~

+(-.OOOOO 34+.00000 51i)(8/~)~ 4- (.OOOOO 06+.00000 19i) [8/x)”

9.11.12 85x<m ker’ s+i kei’ x=-j(z)t$(-x)(I +e3)

1ea1<2XIO-’

9.11.13 85x<- ber’ x+i bei’ x-- (ker’ x+i kei’ s) =g(x))cpp) (I+Q)

where 9.11.14 )cp ( ~ ) = (.70710 68+.70710 68;)

i n.

lQ1<3 x 10-7

+(-,06250 01-.OOOOO Oli)(8/~) + (-.00138 13+.00138 1 li) (8/~)’ + (.OOOOO 05+.00024 52i) ( 8 / ~ ) ~ + (.00003 46 + .00003 38i) (8/2)’ + (.00001 17-.OOOOO 24i)(8/~)~

+(.OOOOO 16-.OOOOO 32i) (8/2)”

1 Methods n Trial values J.(1.66) 9 0 . ooO0o 8 1 .00000 7 10 .OoO03 6 89 .00028 5 679 .00211 4 4292 .01331 3 21473 .06661 2 78829 .24453 1 181957 .56442 0 155964 .48376

We normalize the results by use of the equation 9.1.46, namely

J~(x)+~J~(x)+~J~(x)+ . . . =I

This yields the normalization factor

1/322376=.00000 31019 7

Page 32: Bessel functionsofintegerorder1

BESSEL FUNCTIONS OF INTEGER ORDER 386 and multiplying the trial values by this factor we obtain the required results, given in the third column. As a check we may verify the value of Jo( 1.55) by interpolation in Table 9.1.

(i) In this example it was possible to estimate immediately the value of n=N, say, at which to begin the recurrence. This may not always be the case and an arbitrary value of Nmay have to be taken. The number of correct signifi- cant figures in the final values is the same as the number of digits in the respective trial values. If the chosen N is too small the trial values will have too few digits and insufficient accuracy is obtained in the results. The calculation must then be repeated taking a higher value. On the other hand if N were too large unnecessary effort would be expended. This could be offset to some extent by discarding significant figures in the trial values which are in excess of the number of decimals required in J,,.

(ii) If we had required, say, J0(1.55), J1(1.55), . . ., J10(1.55), each to 5 significant figures, we woiild have found the values of J10(1.55) and Jl1(1.55) to 5 significant figures by interpolation in Table9.3 and then computed by recurrence J8, Js, . . ., Jo, no normalization being required.

Alternatively, we could begin the recurrence at a higher value of N and retain only 5 significant figures in the trial values for n110.

(iii) Exactly similar methods can be used to compute the modified Bessel function I,,@) by means of the relations 9.6.26 and 9.6.36. If x is large, however, considerable cancellation will take place in using the latter equation, and it is preferable to normalize by means of 9.6.37.

Example 2. To evaluate Y,,(1.55), n=O, 1, 2, . . ., fO, each to 5 significant figures.

The recurrence relation

Remarks.

Y,,-l(4 + Y,,+l(4 = (244 Y,,(Z) can be used to compute Y,,(z) in the direction of increasing n both for n<x and n>x, because in the latter event Y,,(x) is a numerically increasing function of n.

We therefore compute Yo( 1.55) and Yl( 1.55) by interpolation in Table 9.1, generate Yz(l .55), Ya(1.55)) . . ., Ylo(1.55) by recurrence and check Ylo(1.55) by interpolation in Table 9.3.

n Y,(1.66) n Y,(1.66) 0 +O. 40225 6 -1.9917X10' 1 -0.37970 7 -1.5100XlW 2 -0.89218 8 -1.3440XlO' 3 -1.9227 9 -1.3722XlW 4 -6.5505 10 - 1.6801 X 10'' 6 -31.886

Remarks. (i) An alternative way of computing Yo(z), should Jo(x), Jz(x), J4(z), . . ., be avail- able (see Example 1)) is to use formula 9.1.89. The other starting value for the recurrence, Yl(x), can then be found from the Wronskian relation Jl(x) Yo(x) -Jo(z) Yl(x) =2/(7rz). This is a convenient procedure for use with an automatic computer.

(ii) Similar methods can be used to compute the modified Bessel function K,,(z) by means of the recurrence relation 9.6.26 and the relation 9.6.54, except that if x is large severe cancellation will occur in the use of 9.6.54 and other methods for evaluating Ko(x) may be preferable, for example, use of the asymptotic expansion 9.7.2 or the poly- nomial approximation 9.8.6.

Example 3. To evaluate J0(.36) and Y0(.36) each to 5 decimals, using the multiplication theorem.

From 9.1.74 we have

We take 2=.4. Then h=.9, (A2-1)(~z)=-.038, and extracting the necessary values of Jk(.4) and Yk(.4) from Tables 9.1 and 9.2, we compute the required results as follows: k a k akJk(.I) akYk(*4 ) 0 +1.0 + .96040 - .60602 1 4-0.038 + .00745 - .06767 2 +0.7220X lo-' + .oooo1 - .00599 3 +0.914Xl0-6 - .00074 4 +0.87x10-7 - .o0011 5 +0.7X10-0 - .woo2

Jo(.36) + .96786 Y0(.36) = - .68065

Remark. This procedure is equivalent to inter- polating by means of the Taylor series

at z=.4, and expressing the derivatives VAk)(z) in terms of g k ( z ) by means of the recurrence rela- tions and differential equation for the Bessel functions.

Example 4. To evaluate Jv(z), J;(x), Y,(x) and X(x) for v=50, 2=75, each to 6 decimals.

We use the asymptotic expansions 9.3.35, 9.3.36, 9.3.43, and 9.3.44. Here z=x/v=3/2. From 9.3.39 we find

1 2 2 (-c)a'z=Z &-arccos -=+.2769653. 3 3

Page 33: Bessel functionsofintegerorder1

BESSEL FUNCTIONS OF INTEGER ORDER 387 Hence

{=-.5567724 and ( 2y4=+1 . 155332 . 1-22

Next,

Interpolating in Table 10.11, we find that

v113=3 .68403l, v213{= -7.556562.

Ai(v213{)= + .299953,

Bi(v2I3{) = - .160565,

Ai‘(v213{) = + .451441,

Bi’(v2I3{) = + 319542.

As a check on the interpolation, we may verify that Aj Bi’- Ai‘Bi = 1 IT.

Interpolating in the table following 9.3.46 we obtain

bo( {) = + -0136, co({) = + .1442.

The contributions of the terms involving al({) and dl({) are negligible, and substituting in the asymptotic expansions we find that

Ja(75) = + 1.155332(50-”X .299953 +50-6BX .451441 X .0136) = +.094077,

Jh(75) = - (4/3)(1.155332)-’(50-‘mX.299953

X.1442+50-2BX.451441)= -.038658,

Ym(75) = - 1.155332 (-5O-”X .160565 +50-6BX.819542X.0136)= +.050335,

Y&(75)= +(4/3)(1.155332)-1(-50-‘BX.160565 X.1442+50-2”X.819542)= +.069543.

As a check we may verify that

JY’- J’Y=2/(75~).

Remarks. This example may also be computed using the Debye expansions 9.3.15,9.3.16, 9.3.19, and 9.3.20. Four terms of each of these series are required, compared with two in the computations above. The closer the argumentader ratio is to .unity, the less effective the Debye expansions become. In the neighborhood of unity the expan- sions 9.3.23, 9.3.24, 9.3.27, and 9.3.28 will furnish results of moderate accuracy; for high-accuracy work the uniform expansions should again be used.

Example 5. To evaluate the 5th positive zero of Jlo(z) and the corresponding value of Jio(z), each to 5 decimals.

We use the asymptotic expansions 9.5.22 and 9.5.23 setting v=10, s=5. From Table 10.11

we find

aa= -7.944134, &‘(a,) = + .947336.

Hence

Interpolating in the table following 9.5.26 we obtain

~({)=+2.888631, h({)=+.98259, .fi ({) = + .0107, F1 ({) = - .001.

The bounds given at the foot of the table show that the contributions of higher terms to the asymptotic series are negligible. Hence

jlo,6=28.88631+.00107+ . . . =28.88738,

2 .947336 J’0ci10*6)=-102/5 2.888631 X .98259

X(l-.00001+ . . .)=-.14381.

Example6. To evaluate the first root of Jo(z)Yo(XZ)-Yo(z)Jo(XZ)=O for A=# to 4 signifi- cant figures.

Let a:’) denote the root. Direct interpolation in Table 9.7 is impracticable owing to the divergence of the differences. Inspection of 9.5.28 suggests that a smoother function is (A-1)ai1). Using Table 9.7 we compute the fol- lowing values

1/x (A- l,ap) 6 0 0.4 3.110

0.6 3.131

0. 8 3.140

1.0 3.142(~)

-12

-7

+21

+9

$2

Interpolating for l/A= .667, we obtain (A-l)ai1)=3.134 and thence the required root ai.’! = 6.268.

Example 7. To evaluate ber, 1.55, bei, 1.55, n=O, 1, 2, . . ., each to 5 decimals.

We use the recurrence relation

Jn-1(2e3r114) +J n+l (ze3rf’4 1

taking arbitrary values zero for J9(xe3rf/4) and l + O i for J8(zP14) (see Example 1).

Page 34: Bessel functionsofintegerorder1

BESSEL FUNCTIONS OF INTEGER ORDER

n

9 8 7 6 5 4 3 2 1 0

E

Real rial value

0 +1 -7 -1

+ 500 - 4447

+ 14989 +11172 - 197012 +281539

+ 106734

Imag. :rial value1

0 0

-7 + 89 - 475 - 203

+ 17446 - 88578

+ 123804 + 195373

+ 207449

bmd

. 00000

. 00000 -. 00002 -. 00003 +. 00181 -. 01494 +. 04614 +. 05994

+. 91004

+. 30763

-. 69531

bei,,z

. 00000

. 00000 -. 00003 +. 00030 -. 00148 -. 00180 +. 06258 -. 29580 +. 36781 +. 59461

+. 72619

The values of ber,z and bei,,z are computed by multiplication of the trial values by the normal- izing factor

1/(294989 - 2201 li) = (.337119 + .025155i) X

obtained from the relation

Adequate checks are furnished by interpolating in Table 9.12 for ber 1.55 and bei 1.55, and the use of a simple sum check on the normalization.

Should ker,,z and kei,z be required they can be computed by forward recurrence using formulas 9.9.14, taking the required starting values for n=O and 1 from Table 9.12 (bee Example 2). If an independent check on the recurrence is required the asymptotic expansion 9.10.38 can be used.

References

Texte

[9.1] E. E. Allen, Analytical approximations, Math. Tables Aids Comp. 8, 240-241 (1954).

[9.2] E. E. Allen, Polynomial approximations to some modified Bessel functions, Math. Tables Aids Comp. 10, 162-164 (1956).

[9.3] H. Bateman and R. C. Archibald, A guide to tables of Bessel functions, Math. Tables Aids Comp. 1, 205-308 (1944).

[9.4] W. G. Bickley, Bessel functions and formulae (Cambridge Univ. Press, Cambridge, England, 1953). This is a straight reprint of part of the preliminaries to [9.21].

[9.5] H. S. Carslaw and J. C. Jaeger, Conduction of heat in solids (Oxford Univ. Press, London, England, 1947).

[9.6] E. T. Copson, An introduction to the theory of functions of a complex variable (Oxford Univ. Press, London, England, 1935).

Higher transcendental functions, vol 2, ch. 7 (McGraw-Hill Book Co., Inc., New York, N.Y., 1953).

[9.8] E. T. Goodwin, Recurrence relations for cross- products of Beasel functions, Quart. J. Mech. Appl. Math. 2, 72-74 (1949).

[9.9] A. Gray, G. B. Mathews and T. M. MacRobert, A treatise on the theory of Bessel functions, 2d ed. (Macmillan and Co., Ltd., London, England; 1931).

[9.10] W. Magnus and F. Oberhettinger, Formeln und Satze fiir die speziellen Funktionen der mathe- matischen Physik, 2d ed. (Springer-Verlag; Berlin, Germany, 1948).

[9.11] N. W. McLachlan, Bessel functions for engineers, 2d ed. (Clarendon Press, Oxford, England, 1955).

[9.12] F. W. J. Olver, Some new asymptotic expansions for Bessel functions of large orders. Proc. Cambridge Philos. SOC. 48, 414-427 (1952).

[9.7] A. Erd6lyi et al.,

[9.13] F. W. J. Olver, The asymptotic expansion of Bessel functions of large order. Philos. Trans. Roy. SOC. London A241, 328-368 (1954).

[9.14] G. Petiau, La th6orie des fonctions de Bessel (Centre National de la Recherche Scientifique, Paris, France, 1955).

[9.15] G. N. Watson, A treatise on the theory of Bessel functions, 2d ed. (Cambridge Univ. Press, Cambridge, England, 1958).

[9.16] R. Weyrich, Die Zylinderfunktionen und ihre Anwendungen (B. G. Teubner, Leipzig, Germany, 1937).

[9.17] C. 5. Whitehead, On a generalization of the func- tions ber z, bei 2, ker 2, kei 2. Quart. J. Pure Appl. Math. 42, 316-342 (1911).

[9.18] E. T. Whittaker and G. N. Watson, A course of modern analysis, 4th ed. (Cambridge Univ. Press, Cambridge, England, 1952).

Tables

(9.191 J. F. Bridge and S. W. Angrist, An extended table of roots of JA(z) Yi(@z) -J:(@z) Yi(z)=O, Math. Comp. 16, 198-204 (1962).

[9.20] British Association for the Advancement of Science, Bessel functions, Part I. Functions of orders zero and unity, Mathematical Tables, vol. VI (Cambridge Univ. Press, Cambridge, England, 1950).

[9.21] British Association for the Advancement of Science, Bessel functions, Part 11. Functions of positive integer order, Mathematical Tables, vol. x (Cambridge Univ. Press, Cambridge, England, 1952).

[9.22] British Association for the Advancement of Science, Annual Report (J. R. Airey), 254 (1927).

[9.23] E. Cambi, Eleven- and fifteen-place tables of Bessel functions of the first kind, to all significant orders (Dover Publications, Inc., New York, N.Y., 1948).

Page 35: Bessel functionsofintegerorder1

BESSEL FUNCTIONS OF INTEGER ORDER 389

[9.24] E. A. Chistova, Tablitsy funktsii Besselya ot deistvitel’nogo argumenta i integralov ot nikh (Izdat. Akad. Nauk SSSR, Moscow, U.S.S.R., 1958). (Table of Bessel functions with real argument and their integrals).

[9.25] H. B. Dwight, Tables of integrals and other mathe- matical data (The Macmillan Co., New York, N.Y., 1957).

This includes formulas for, and tables of Kelvin functions.

[9.26] H. B. Dwight, Table of roots for natural frequencies in coaxial type cavities, J. Math. Phys. 27,

This gives zeros of the functions 9.6.27 and 9.6.30

[9.27] V. N. Faddeeva and M. K. Gavurin, Tablitsy funktsii Besselia J.(z) tselykh nomerov ot 0 do 120 (lzdat. Akad. Nauk SSSR, Moscow, U.S.S.R., 1950). (Table of J,(z) for orders 0 to 120).

[9.28] L. Fox, A short table for Bessel functions of integer orders and large arguments. Royal Society Shorter Mathematical Tables No. 3 (Cambridge Univ. Press, Cambridge, England, 1954).

[9.29] E. T. Goodwin and J. Staton, Table of J3G0..t), Quart. J. Mech. Appl. Math. 1, 220-224 (1948).

[9.30] Harvard Computation Laboratory, Tables of the Beasel functions of the first kind of orders 0 through 135, vola. 3-14 (Harvard Univ. Press, Cambridge, Mass., 1947-1951).

[9.31] K. Hayashi, Tafeln der Besselschen, Theta, Kugel- und anderer Funktionen (Springer, Berlin, Ger- many, 1930).

[9.32] E. Jahnke, F. Emde, and F. Loach, Tablea of higher functions, ch. IX, 6th ed. (McGraw-Hill Book Co., Inc., New York, N.Y., 1960).

[9.33] L. N. Karmazina and E. A. Chistova, Tablitsy funktsii Besselya ot mnimogo arguments i integralov ot nikh (Izdat. Akad. Nauk SSSR, Moscow, U.S.S.R., 1958). (Tables of Bessel

84-89 (1948).

for n=0,1,2,3.

functions with imaginary argument and their integrals).

[9.34] Mathematical Tables Project, Table of fn(z)=nl(Hz)-nJ.(z). J. Math. Phys. 23, 45-60 (1944).

[9.35] National Bureau of Standards, Table of the Bessel functions Jo(z) and JI(z) for complex arguments, 2d ed. (Columbia Univ. Press, New York, N.Y., 1947).

[9.36] National Bureau of Standards, Tables of the Bessel functions Yo@) and Yl(z) for complex arguments (Columbia Univ. Press, New York, N.Y., 1950).

[9.37] National Physical Laboratory Mathematical Tables, vol. 5, Chebyshev series for mathematical func- tions, by C. W. Clenshaw (Her Majesty’s Sta- tionery Office, London, England, 1962).

[9.38] National Physical Laboratory Mathematical Tables, vol. 6, Tables for Bessel functions of moderate or large orders, by F. W. J. Olver (Her Majesty’s Stationery Office, London, England, 1962).

[9.39] L. N. Nosova, Tables of Thomson (Kelvin) functions and their first derivatives, translated from the Russian by P. Basu (Pergamon Press, New York, N.Y., 1961).

[9.40] Royal Society Mathematical Tables, vol. 7, Bessel functions, Part 111. Zeros and associated values, edited by F. W. J. Olver (Cambridge Univ. Press, Cambridge, England, 1960).

The introduction includes many formulas con- nected with zeros.

[9.41] Royal Society Mathematical Tables, vol. 10, Bessel functions, Part IV. Kelvin functions, by A. Young and A. Kirk (Cambridge Univ. Press, Cambridge, England, 1963).

The introduction includes many formulas for Kelvin functions.

19.421 W. Sibagaki, 0.01 ’% tables of modified Bessel functions, with the account of the methods used in the calculation (Baifukan, Tokyo, Japan, 1955).


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