minor improvements

chapter09/linRegEm.m

@@ -14,7 +14,7 @@
     beta = 0.5;
 end
 [d,n] = size(X);
-
+I = eye(d);
 xbar = mean(X,2);
 tbar = mean(t,2);
 
@@ -39,12 +39,12 @@
     llh(iter) = 0.5*(d*log(alpha)+n*log(beta)-alpha*m2-beta*e2-logdetA-n*log(2*pi));  % 3.86
     if abs(llh(iter)-llh(iter-1)) < tol*abs(llh(iter-1)); break; end
 
-    V = inv(U);
-    trS = dot(V(:),V(:));    % A=inv(S)
+    invU = U'\I;
+    trS = dot(invU(:),invU(:));    % A=inv(S)
     alpha = d/(m2+trS);   % 9.63
 
-    UX = U'\X;
-    trXSX = dot(UX(:),UX(:));
+    invUX = U'\X;
+    trXSX = dot(invUX(:),invUX(:));
     beta = n/(e2+trXSX);  % 9.68 is wrong
 end
 w0 = tbar-dot(m,xbar);

chapter10/linRegVb.m

@@ -8,7 +8,6 @@
 %   model: trained model structure
 %   energy: variational lower bound
 % Written by Mo Chen (sth4nth@gmail.com).
-[m,n] = size(X);
 if nargin < 3
     a0 = 1e-4;
     b0 = 1e-4;
@@ -20,6 +19,7 @@
     c0 = prior.c;
     d0 = prior.d;
 end
+[m,n] = size(X);
 I = eye(m);
 xbar = mean(X,2);
 tbar = mean(t,2);

chapter10/rvmRegVb.m

@@ -8,7 +8,6 @@
 %   model: trained model structure
 %   energy: variational lower bound
 % Written by Mo Chen (sth4nth@gmail.com).
-[m,n] = size(X);
 if nargin < 3
     a0 = 1e-4;
     b0 = 1e-4;
@@ -20,6 +19,7 @@
     c0 = prior.c;
     d0 = prior.d;
 end
+[m,n] = size(X);
 idx = (1:m)';
 dg = sub2ind([m,m],idx,idx);
 I = eye(m);

chapter14/mixLinReg.m

@@ -45,7 +45,6 @@
     if abs(llh(iter)-llh(iter-1)) < tol*abs(llh(iter)); break; end
 end
 llh = llh(2:iter);
-label = max(R,[],1);
 model.alpha = alpha; % mixing coefficient
 model.beta = beta; % mixture component precision
 model.W = W;  % linear model coefficent