function mask = getgmask(phi,m,n)
global nstate
nstate = m;

%y = zeros(1,n);
dims = repmat([m],[1 n]);

global FN
FN{n} = phi;


global nstate
nstate = m;

y = zeros(1,n);
dims = repmat([m],[1 n]);

xx = list_all_ind(repmat([m],[1 n-1]));

global FN
FN{n} = phi;

mask = {};

for i=1:n
  for xind = 1:size(xx,1)
    %for xind = 1;
    xl = xx(xind,1:i-1);
    xr = xx(xind,i:n-1);
    fv = [];
    for xj = 1:m
      x = [xl xj xr];
      fv(end+1) = F(x);
    end
    fvu = unique(round(fv*1e5));
    if length(fvu)==2
      ii = find(fv-min(fv)<1e-8);
      mask{1,i} = ii;
      break;
    else
      %'hmmm'
      %keyboard
    end
  end
end
return



function r = F(x)
global nstate
lenseq = length(x);
global FN
FF = FN{lenseq};
ind = coord2ind(x,(repmat(nstate,1,lenseq)));
r = FF(ind);
return


function b = myeq(x,y)
b = abs(x-y) < 1e-9;
return