added sparse coding demo for rvmRegVb

chapter10/demo_rvm.m

@@ -0,0 +1,34 @@
+% demos for ch07
+
+%% sparse signal recovery demo
+clear; close all; 
+
+d = 512; % signal length
+k = 20;  % number of spikes
+n = 100; % number of measurements
+%
+% random +/- 1 signal
+x = zeros(d,1);
+q = randperm(d);
+x(q(1:k)) = sign(randn(k,1)); 
+
+% projection matrix
+A = unitize(randn(d,n),1);
+% noisy observations
+sigma = 0.005;
+e = sigma*randn(1,n);
+y = x'*A + e;
+
+[model,llh] = rvmRegVb(A,y);
+plot(llh);
+m = model.w;
+
+h = max(abs(x))+0.2;
+x_range = [1,d];
+y_range = [-h,+h];
+figure;
+subplot(2,1,1);plot(x); axis([x_range,y_range]); title('Original Signal');
+subplot(2,1,2);plot(m); axis([x_range,y_range]); title('Recovery Signal');
+
+
+