diff DL/two-step DL/dico_decorr.m @ 156:a4d0977d4595 danieleb

First branch commit, danieleb

--- a/DL/two-step DL/dico_decorr.m	Fri Jul 29 12:35:52 2011 +0100
+++ b/DL/two-step DL/dico_decorr.m	Tue Aug 30 11:12:31 2011 +0100
@@ -9,6 +9,8 @@
     %   Result:
     %   dico: a dictionary close to the input one with coherence mu.
     
+    eps = 1e-6; % define tolerance for normalisation term alpha
+    
     % compute atom weights
     if nargin > 2
         rank = sum(amp.*amp, 2);
@@ -20,7 +22,7 @@
     % coherence mu. niter can be adjusted to needs.
     niter = 1;
     while niter < 5 && ...
-            max(max(abs(dico'*dico -eye(length(dico))))) > mu + 10^-6
+            max(max(abs(dico'*dico -eye(length(dico))))) > mu + eps
         % find pairs of high correlation atoms
         colors = dico_color(dico, mu);
         
@@ -36,7 +38,7 @@
                 
                 % update the atom
                 corr = dico(:,index(1))'*dico(:,index(2));
-                alpha = sqrt((1-mu*mu)/(1-corr*corr));
+                alpha = sqrt((1-mu*mu)/(1-corr^2+eps));
                 beta = corr*alpha-mu*sign(corr);
                 dico(:,index(2)) = alpha*dico(:,index(2))...
                     -beta*dico(:,index(1));