function?[ldagammaldaphilikelihood]=ldainference（dab）

%?LDAINFERENCE
%
%?function?[ldagammaldaphilikelihood]=ldainference（dab）
%
%?Variational?inference?algorithm?for?the?LDA?Model
%
%?input:?（document?vector?corpus?parameters
%????????d?is?a?Nx1?word?occurrence?vector
%????????a?is?a?kx1?dirichlet?parameter
%????????b?is?a?kxV?matrix
%?output:?（variational?parameters）
%????????ldagamma?is?a?kx1?vector
%????????ldaphi?is?a?kxN?matrix
%????????likelihood?is?the?（variational）?log?likelihood?of?
%????????the?document.
%
%?where?V?is?the?size?of?the?vocabulary
%???????k?is?the?#?of?topics
%???????N?is?the?number?of?words?in?d?（sum（d））
%
%?Authors:?Jonathan?Huang???????（jch1?at?cs.cmu.edu）
%??????????Tomasz?Malisiewicz??（tomasz?at?cmu.edu）

epsilon?=?.00001;?%?convergence?criterion

V?=?size（b2）;
k?=?length（a）;?
N?=?length（d）;

%?initialize?variational?parameters
ldaphi?=?repmat（1/kkN）;
ldagamma?=?a?+?repmat（N/kk1）;

oldphi=ldaphi;
oldgamma=ldagamma;

maxiter?=?200;
numiter?=?1;
change=2*epsilon;
%?until?convergence...
while?change>epsilon
????oldphi=ldaphi;
????oldgamma=ldagamma;
????
	ldaphi?=?b（:d）.*repmat（exp（digamma（ldagamma））1N）;
????ldaphi?=?ldaphi?./?repmat（sum（ldaphi）k1）;
????ldagamma?=?a?+?sum（ldaphi‘）‘;
????
????change?=?max（max（abs（ldagamma-oldgamma））?...
????????max（max（abs（ldaphi-oldphi））））;

	numiter?=?numiter?+?1;??
????if?（numiter?>?maxiter）
????????break
????end
end

dig?=?digamma（ldagamma）;
digsum?=?digamma（sum（ldagamma））;
likelihood=gammaln（sum（a））-sum（gammaln（a））?+?sum（（a-1）.*（dig-digsum））?...
????-?gammaln（sum（ldagamma））+sum（gammaln（ldagamma））?...
	-?sum（（ldagamma-1）.*（dig-digsum））?-?sum（sum（ldaphi.*log（ldaphi）））?...
	+?（dig-digsum）‘*sum（ldaphi2）?+?sum（sum（ldaphi.*log（b（:d））））;

?屬性????????????大小?????日期????時間???名稱
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?????目錄??????????0??2008-04-22?17:08??Jonathan?Huang

?????文件???????1812??2008-04-22?16:59??Jonathan?Huang\ldainference.m

?????文件???????3991??2008-04-22?16:59??Jonathan?Huang\lda_param_est.m

?????文件???????1401??2008-04-22?16:59??Jonathan?Huang\trainLDA.m

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?????????????????7204????????????????????4