%Binomial.m
%Math 128B Spring 2005
% call once Binomial('init') to load Binomial.mat datafile
% subsequent calls to Binomial('3'), Binomial('4'), etc.
% will return b=B3=[1 2 1], b=B4=[1 3 3 1], etc.

function b	= Binomial(selector)
persistent	BinCoef

switch selector
case 'init'
	%initialize by loading data file
	BinCoef	= load('Binomial.mat');
	b	= 0;
otherwise
	%retrieve variable from BinCoef data
	%B1=[1], B2=[1 1], B3=[1 2 1]
	%in general, "BN"=[nC0,...,nCn] where (n=N-1)
	b	= eval(['BinCoef.B' num2str(selector)]);
end

return

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%% Binomial.mat created with following code %%%
%creates variables Bn=[nC0,...,nCn]
clear
B1	= 1;
Bn	= 'B1';

for n=1:40
	Bn1	= ['B' num2str(n+1)];
	evalstr	= [Bn1 '= [0,' Bn '] + [' Bn ',0]'];
	eval(evalstr);
	Bn	= Bn1;
end

save('Binomial.mat')