343     intermediate_val = Math.tan(lat_rad) + (1 / Math.cos(lat_rad))
344     begin
345       ytile = ((1 - (Math.log(intermediate_val) / Math::PI)) / 2 * n).floor
346     rescue Errno::ERANGE => e
347       puts @path.inspect
348       puts "#{lat_rad}"
349       puts "#{intermediate_val}"
350       raise e
351     end