function P1 = reorderP(P,m,n,pi)
% pi is a row vector permutation
dims = repmat([m],[1 n]);
P1 = 0*P;
for xi = 1:m^n
  x = ind2coord(xi,dims);
  y = applyperm(pi,x);
  yi = coord2ind(y,dims);
  P1(yi) = P(xi);
end
return

function y = applyperm(pi,x)
y = x;
for i=1:length(x)
  y(i) = x(pi(i));
end
return