# File lib/Matriz_dispersa.rb, line 7
   def initialize(m)
   @filas = m.size
   @cols = m[1].size

   aux_m = Hash.new
   @filas.times do |i|          
      @cols.times do |j|                
         if m[i][j] != 0
            aux_m[i.to_s+"_"+j.to_s] = m[i][j]
         end
      end
   end
   @matriz = aux_m
   end