indexing
	description: "Objects to which numerical operations are applicable"
	note: "The model is that of a commutative ring."
	status: "See notice at end of class"
	date: "$Date$"
	revision: "$Revision$"

deferred class interface
	NUMERIC

feature -- Access

	one: like Current
			-- Neutral element for "*" and "/"
		ensure
			result_exists: Result /= void

	zero: like Current
			-- Neutral element for "+" and "-"
		ensure
			result_exists: Result /= void

feature -- Status report

	divisible (other: like Current): BOOLEAN
			-- May current object be divided by other?
		require
			other_exists: other /= void

	exponentiable (other: NUMERIC): BOOLEAN
			-- May current object be elevated to the power other?
		require
			other_exists: other /= void

feature -- Basic operations

	infix "*" (other: like Current): like Current
			-- Product by other
		require
			other_exists: other /= void
		ensure
			result_exists: Result /= void

	prefix "+": like Current
			-- Unary plus
		ensure
			result_exists: Result /= void

	infix "+" (other: like Current): like Current
			-- Sum with other (commutative).
		require
			other_exists: other /= void
		ensure
			result_exists: Result /= void
			commutative: equal (Result, other + Current)

	prefix "-": like Current
			-- Unary minus
		ensure
			result_exists: Result /= void

	infix "-" (other: like Current): like Current
			-- Result of subtracting other
		require
			other_exists: other /= void
		ensure
			result_exists: Result /= void

	infix "/" (other: like Current): like Current
			-- Division by other
		require
			other_exists: other /= void
			good_divisor: divisible (other)
		ensure
			result_exists: Result /= void

invariant

		-- from ANY
	reflexive_equality: standard_is_equal (Current)
	reflexive_conformance: conforms_to (Current)

indexing
	library: "[
			EiffelBase: Library of reusable components for Eiffel.
	]"
	status: "[
			Copyright 1986-2001 Interactive Software Engineering (ISE).
			For ISE customers the original versions are an ISE product
			covered by the ISE Eiffel license and support agreements.
	]"
	license: "[
			EiffelBase may now be used by anyone as FREE SOFTWARE to
			develop any product, public-domain or commercial, without
			payment to ISE, under the terms of the ISE Free Eiffel Library
			License (IFELL) at http://eiffel.com/products/base/license.html.
	]"
	source: "[
			Interactive Software Engineering Inc.
			ISE Building
			360 Storke Road, Goleta, CA 93117 USA
			Telephone 805-685-1006, Fax 805-685-6869
			Electronic mail <info@eiffel.com>
			Customer support http://support.eiffel.com
	]"
	info: "[
			For latest info see award-winning pages: http://eiffel.com
	]"

end -- class NUMERIC