class interface DOUBLE_REF

feature(s) from HASHABLE
   hash_code: INTEGER
      --  The hash-code value of Current.

      ensure
         good_hash_value: Result >= 0

feature(s) from NUMERIC
   infix "+" (other: like Current): like Current
      --  Sum with 'other' (commutative).

      require
         other /= Void

   infix "-" (other: like Current): like Current
      --  Result of substracting other.

      require
         other /= Void

   infix "*" (other: like Current): like Current
      --  Product by other.

      require
         other /= Void

   infix "/" (other: like Current): like Current
      --  Division by other.

      require
         other /= Void;
         divisible(other)

   infix "^" (exp: INTEGER): like Current
      --  Current raised to exp-th power.

      require
         exp >= 0

   prefix "+": like Current
      --  Unary plus of Current.


   prefix "-": like Current
      --  Unary minus of Current.


   divisible (other: like Current): BOOLEAN
      --  May Current be divided by other ?

      require
         other /= Void

   one: like Current
      --  Neutral element for "*" and "/".


   zero: like Current
      --  Neutral element for "+" and "-".


   sign: INTEGER
      --  Sign of Current (0 -1 or 1).

      ensure
         - 1 <= Result;
         Result <= 1

   infix "<" (other: like Current): BOOLEAN
      --  Is Current strictly less than other?

      require
         other_exists: other /= Void
      ensure
         asymmetric: Result implies not (other < Current)

   infix ">" (other: like Current): BOOLEAN
      --  Is Current strictly greater than other?

      require
         other_exists: other /= Void
      ensure
         definition: Result = (other < Current)

feature(s) from COMPARABLE
   infix "<=" (other: like Current): BOOLEAN
      --  Is Current less than or equal other?

      require
         other_exists: other /= Void
      ensure
         definition: Result = (Current < other or is_equal(other))

   infix ">=" (other: like Current): BOOLEAN
      --  Is Current greater than or equal than other?

      require
         other_exists: other /= Void
      ensure
         definition: Result = (other <= Current)

   in_range (lower, upper: like Current): BOOLEAN
      --  Return true if Current is in range [lower..upper]

      ensure
         Result = (Current >= lower and Current <= upper)

   compare (other: like Current): INTEGER
      --  If current object equal to other, 0;
      --  if smaller,  -1; if greater, 1.

      require
         other_exists: other /= Void
      ensure
         equal_zero: Result = 0 = is_equal(other);
         smaller_negative: Result = - 1 = Current < other;
         greater_positive: Result = 1 = Current > other

   three_way_comparison (other: like Current): INTEGER
      --  If current object equal to other, 0;
      --  if smaller,  -1; if greater, 1.

      require
         other_exists: other /= Void
      ensure
         equal_zero: Result = 0 = is_equal(other);
         smaller_negative: Result = - 1 = Current < other;
         greater_positive: Result = 1 = Current > other

   min (other: like Current): like Current
      --  Minimum of Current and other.

      require
         other /= Void
      ensure
         Result <= Current and then Result <= other;
         compare(Result) = 0 or else other.compare(Result) = 0

   max (other: like Current): like Current
      --  Maximum of Current and other.

      require
         other /= Void
      ensure
         Result >= Current and then Result >= other;
         compare(Result) = 0 or else other.compare(Result) = 0

feature(s) from DOUBLE_REF
   item: DOUBLE

feature(s) from DOUBLE_REF
   set_item (value: like item)

   out_in_tagged_out_memory
      --  Append terse printable represention of current object
      --  in tagged_out_memory.


   fill_tagged_out_memory
      --  Append terse printable represention of current object
      --  in tagged_out_memory.



end of DOUBLE_REF