Re: help (with Bessel)

[frerejacque <daniel frerejacque free fr>]

> chengj a écrit :
>
> Hi !
> Now I found a big problem : bessely(4.5,6) = -0.9846543023 in OPEN
> OFFICE
>                                                           =-0.98465430170
> in excel
> But when I compute Bessely using MATLAB ,the result was
> -0.05459791739132
> ( -0.05459791739132197 in Mathematica)
>
>
> some one who can tell me which one is right ?????
>
> Thank you very much !!!
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Well,
there is a book issued in 1966 by the
National Bureau of Standards for $6.50 in 1966
and tabulating a lot of special functions
with some mathematics too:

Assuming the question is the value of
the Bessel function:
Y, of fractional order 4.5 for x=6.

Looking at page 437:

Y(4.5, x) = sqrt((2x)/pi)* y(4, x)
---------------------------------
y beeing the spherical bessel function
of the second kind.

y(4,x) is tabulated to 5 places in table 10.2 
page 462 and
y(4, 6)= -2.7936E-2.
back to the hand computing device
and 
Y(4.5, 6) = sqrt(12/pi)*-2.7936E-2
= - 0.054598
with five decimal places:

CONCLUSION: The value given in
Mathematica and Mathlab agrees with
ye old math tables.

Why OPPENOFFICE and EXCEL do'nt is an 
other problem

Daniel Frerejacque
Paris (France)
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