function ShowPCG()
A = delsq(numgrid('L',100));

b = A*ones(length(A),1);
kMax = 250;
close all
[x,rVals] = cg2(A,b,2*kMax);
semilogy(rVals)
title(sprintf('cg    n = %1d',length(b)),'Fontsize',18)
ylabel('|| A*xk - b ||','fontsize',18)
xlabel('k','fontsize',18)
shg

figure
G = cholinc(A,0);
[x,rVals] = pcg2(A,b,kMax,G);
semilogy(rVals)
title('pcg','fontsize',18)
ylabel('|| A*xk - b ||','fontsize',18)
xlabel('k','fontsize',18)
shg