How to only follow certain links with matlab spider

Hi I am struggling with only allowing certain urls to be followed when using a spider to build a web graph. Basically I only want the spider to follow links that point to the uni server( shef.ac.uk), any other urls need to be discarded, opposed to the current state were all links are followed. Probably quiet a simple fix.

U = cell(n,1);
hash = zeros(n,1);
L = logical(sparse(n,n));
m = 1;
U{m} = root;
hash(m) = hashfun(root);

for j = 1:n
    try
        disp(['open ' num2str(j) ' ' U{j}])
        page = urlread(U{j});
    catch
        disp(['fail ' num2str(j) ' ' U{j}])
        continue
    end

      for f = findstr('http:',page);

          e = min(findstr('"',page(f:end)));
          if isempty(e), continue, end
          url = deblank(page(f:f+e-2));
          url(url<' ') = '!';
          if url(end) == '/', url(end) = []; end

          skips = {'.gif','.jpg','.ico'};
          skip = any(url=='!') | any(url=='?');
          k=0;
          while ~skip && (k < length(skips))
              k = k+1;
              skip = ~isempty(findstr(url,skips{k}));
          end
          if skip
              if isempty(findstr(url,'.gif')) & isempty(findstr(url,'.jpg'))
                  disp([' skip' url])
              end
              continue
          end

          i=0;
          for k = find(hash(1:m) == hashfun(url))';
              if isequal(U{k},url)
                  i = k;
                  break
              end
          end

          if (i == 0) & (m < n)
              m = m+1;
              U{m} = url;
              hash(m) = hashfun(url);
              i=m;
          end

          if i > 0
              disp([' link ' int2str(i) ' ' url])
              L(i,j) = 1;
          end
      end
  end