    # File lib/rubygame/events/joystick_events.rb, line 61
          def initialize( joystick_id, axis, value )

            unless joystick_id.kind_of?(Fixnum) and joystick_id >= 0
              raise ArgumentError, "joystick_id must be an integer >= 0"
            end

            @joystick_id = joystick_id

            unless axis.kind_of?(Fixnum) and axis >= 0
              raise ArgumentError, "axis must be an integer >= 0"
            end

            @axis = axis

            unless value.kind_of?(Numeric) and value.between?(-1.0, 1.0)
              raise ArgumentError, "value must be a number in the range (-1.0)..(1.0)"
            end

            @value = value.to_f

         end