Lec4 SpFn Bessel

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    Special Functions

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    Bessel Functions

    Applications

    EM waves in a cylindrical waveguide

    Vibration in a circular membrane

    G

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    Bessel Functions

    Applications

    Heat conduction in circular Rods

    Frequency Spectrum in FM

    G

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    Bessel Functions

    Bessels Eq. of order , 0 0 is a regular singular point

    =

    +

    =

    1 +

    =

    +

    =

    ++

    =

    + 0

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    Bessel Functions

    =

    1 +

    =

    +

    =

    +

    =

    + 0

    1 +

    =

    1 +

    , 0,

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    Bessel Functions

    0 2 , 2,3, 5 0 1

    1

    2! 1 2 1=

    1! 1

    2

    +

    =

    1

    ! 1

    2

    +Bessel Functions of the first

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    Bessel Functions

    =

    1! 1 2 +

    1 1! 2

    2! 2

    63! 26

    2

    21!2!

    5252!3!

    7273!4!

    Bessel Function of the first

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    Bessel Functions

    Bessels Eq.

    0If is not integer, then the general solution is:

    = 1! 1 2

    +

    =

    1! 1

    2

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    Bessel Functions

    Ex. Show that the general solution of Bessels Eq.

    14 0is:

    / /

    where

    / 2 , /

    2

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    Bessel Functions

    1

    4 1

    2So the solution is given by: / /

    / =

    1! 1/2 1

    2

    /

    2=

    1! 1/2

    2

    2

    =

    1

    (2)!

    1/2

    2

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    Bessel FunctionsEx. Find the general solution of Bessels Eq.

    0 0,

    =

    2 =

    =

    + =

    1 0 0,

    14

    12! 1 !

    2

    12! 1

    12

    2

    13! 1

    12

    13

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    Bessel Functions

    Properties

    For 0,1,2,1. 12. 1

    =

    1

    ! 12

    =

    1+ ! 1

    2

    +

    =

    1!

    1=

    1! 1

    2

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    Bessel Functions

    Bessel Functions of the second kind (Neumann-Weber)

    0then the general solution can be written as:

    = 1! 1 2

    +

    lim ()

    Heinrich M. Weber

    German Math.

    1842-1913

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    Bessel Functions

    Bessel Functions of the second kind (Neumann-Weber)

    0then the general solution can be written as:

    =

    1

    ! 12

    +

    lim ()

    2

    2

    2

    =

    1 1

    !

    1

    2

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    Bessel FunctionsEx. Find the general solution of Bessels Eq.

    9 4 0 3 3 , 9

    4 0

    3 3In general, solution of 0

    is

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    Bessel Functions

    Properties

    For 0,1,2,1.

    2. +

    3. + 4. + 2

    =

    1!

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    Bessel Functions

    Ex. Express5/ in terms of trigonometric functions+ 2 5/

    3/ /

    1

    Ex. Show that

    +

    31/ / /