besinu.m

很多matlab的源代码

function In = besinu(m,x)
% BESINU Spherical Bessel function i
%
%	I = BESINU(N,X) Spherical Bessel function i(x) of order N
%	NOTE: N must be a scalar
%
%	NOTE: For a definition, see Abramowitz and Stegun
%
%       BESINU (with no input arguments) invokes the following example:
%
%	% Compute i(x) of order 3 for xx =[1 2 3 4 5]
%	  >> xx = 1:5
%         >> ixx = besinu(3,xx)


% ADSP Toolbox: Version 2.0 
% For use with "Analog and Digital Signal Processing", 2nd Ed.
% Published by PWS Publishing Co.
%
% Ashok Ambardar, EE Dept. MTU, Houghton, MI 49931, USA
% http://www.ee.mtu/faculty/akambard.html
% e-mail: [e-mail]
% Copyright (c) 1998


if nargin==0,help besinu,disp('Strike a key to see results of the example')
pause,xx=1:5,ixx=besinu(3,xx),return,end

z=x+(x==0);n=m+0.5;
if exist('besseli')==2,
In = sqrt(pi/2)*besseli(n,z)./sqrt(z);
else
tol=2e-16;
sqrt_pi = 1.7724538509055160272;
sqrt2=1.4142135623730950488;
In=sqrt_pi*besin(n,z,tol)/(sqrt2)./sqrt(z);
end
In=In.*(x~=0)+(x==0 & m==0);