ilup.m

various matlab programs to slove various problems

function [a,lev] = ilup (a,p)
[n,n]=size(a);
for i=1:n,  for j=1:n
    if (a(i,j) ~= 0)| (i==j)
      lev(i,j)=0;
    else
      lev(i,j)=Inf;
    end
end,  end
for i=2:n,  
  for k=1:i-1
    if lev(i,k) <= p
      a(i,k)=a(i,k)/a(k,k);
      for j=k+1:n
        a(i,j)=a(i,j)-a(i,k)*a(k,j);
        if a(i,j) ~= 0
          lev(i,j)=min(lev(i,j),lev(i,k)+lev(k,j)+1);
        end
      end
    end
  end
  for j=1:n, if lev(i,j) > p, a(i,j) = 0; end, end 
end
return