function [x,cnt] = pagerankpow(G)
% PAGERANKPOW PageRank by power method with no matrix operations.
% x = pagerankpow(G) is the PageRank of the graph G.
% [x,cnt] = pagerankpow(G) also counts the number of iterations.
% There are no matrix operations. Only the link structure
% of G is used with the power method.
% Copyright 2012 Cleve Moler and The MathWorks, Inc.
% Link structure
[n,n] = size(G);
for j = 1:n
L{j} = find(G(:,j));
c(j) = length(L{j});
end
% Power method
p = .85;
delta = (1-p)/n;
x = ones(n,1)/n;
z = zeros(n,1);
cnt = 0;
while max(abs(x-z)) > .0001
z = x;
x = zeros(n,1);
for j = 1:n
if c(j) == 0
x = x + z(j)/n;
else
x(L{j}) = x(L{j}) + z(j)/c(j);
end
end
x = p*x + delta;
cnt = cnt+1;
end