clear;
np = 8;
I = double(checkerboard(np)); 
m = size(I,1);

H = fspecial('gaussian',50,2);
B = imfilter(I,H,'replicate');
subplot(131);imshow(I,[]);     title('Original');
subplot(132);imshow(B,[]); title('Blurred');

tol = 1.e-2; maxit = 1000;
u0 = B(:); t = 2.e+3;

t0 = cputime;
[u,iter,nf] = zGD(@TVL2B,u0,tol,maxit,u0,t,m,H);
tcpu = cputime - t0;
[f,g] = TVL2B(u,u0,t,m,H);
fprintf(' zGD:  iter %3i, nf = %4i, tcpu = %6.2e\n',iter,nf,tcpu)
fprintf(' zGD:  f = %12.6e, norm(g) = %9.3e \n\n',f,norm(g))

if exist('myGD');
t0 = cputime;
[u,iter,nf] = myGD(@TVL2B,u0,tol,maxit,u0,t,m,H);
tcpu = cputime - t0;
[f,g] = TVL2B(u,u0,t,m,H);
fprintf('myGD:  iter %3i, nf = %4i, tcpu = %6.2e\n',iter,nf,tcpu)
fprintf('myGD:  f = %12.6e, norm(g) = %9.3e \n\n',f,norm(g))
end

U = reshape(u,m,m);
subplot(133);imshow(U,[]); title('Restored');