modified TODO

TODO.txt

@@ -1,9 +1,8 @@
 TODO: 
+chapter12: sqaure root update for EM and VB for PCA and FA
+chapter10: compute bound terms inside each factors
 chapter10/12: prediction functions for VB
-chapter10: compute bound terms inside each factors, 
 chapter07: update beta for sequential rvm
-chapter13: constrained filter (like pcaEMc)
-chapter12: constrained VB pca
 
 Help:
 standardize help descrtiption: add input/output description

common/invpd.m

@@ -0,0 +1,10 @@
+function W = invpd(M)
+% Compute A\B where A is a positive definite matrix
+%   A: a positive difinie matrix
+% Written by Michael Chen ([email protected]).
+[U,p] = chol(M);
+if p > 0
+    error('ERROR: the matrix is not positive definite.');
+end
+V = inv(U);
+W = V*V';