# File lib/cassiopee-mt.rb, line 42
   def searchExact(pattern)
        len = @sequence.length
        if(@min_position>0)
          min = @min_position
         else
          min = 0  
        end
         if(@max_position>0)
           max = @max_position
         else
           max= @sequence.length
        end
        len = max - min 
        if(len<MINSEQSIZE)
              @maxthread=1
        end
        nb = len.div(maxthread)
        (1..maxthread).each do |i|
                        crawler = Crawler.new
                        setParams(crawler,i)
                        curmax = min + nb
                        if(i==maxthread)
                                curmax = max
                        end
                        crawler.filter_position(min,curmax)
                        $log.debug("Start new Thread between " << min.to_s << " and " << curmax.to_s)
                        @th[i-1] = Thread.new{ Thread.current["matches"] = crawler.searchExact(pattern) }
                        min = curmax + 1
        end
        @th.each {|t| t.join; t["matches"].each { |m| @matches << m }}
        return @matches
   end