-----------------------------------------------------------------------------
---
+-- |
-- Module : Data.Ratio
-- Copyright : (c) The University of Glasgow 2001
--- License : BSD-style (see the file libraries/core/LICENSE)
+-- License : BSD-style (see the file libraries/base/LICENSE)
--
-- Maintainer : libraries@haskell.org
--- Stability : provisional
+-- Stability : stable
-- Portability : portable
--
--- $Id: Ratio.hs,v 1.1 2001/06/28 14:15:02 simonmar Exp $
---
-- Standard functions on rational numbers
--
-----------------------------------------------------------------------------
import GHC.Real -- The basic defns for Ratio
#endif
+#ifdef __HUGS__
+import Hugs.Prelude(Ratio(..), (%), numerator, denominator)
+#endif
+
+#ifdef __NHC__
+import Ratio (Ratio(..), (%), numerator, denominator, approxRational)
+#else
+
-- -----------------------------------------------------------------------------
-- approxRational
--- @approxRational@, applied to two real fractional numbers x and epsilon,
--- returns the simplest rational number within epsilon of x. A rational
--- number n%d in reduced form is said to be simpler than another n'%d' if
--- abs n <= abs n' && d <= d'. Any real interval contains a unique
--- simplest rational; here, for simplicity, we assume a closed rational
+-- | 'approxRational', applied to two real fractional numbers @x@ and @epsilon@,
+-- returns the simplest rational number within @epsilon@ of @x@.
+-- A rational number @y@ is said to be /simpler/ than another @y'@ if
+--
+-- * @'abs' ('numerator' y) <= 'abs' ('numerator' y')@, and
+--
+-- * @'denominator' y <= 'denominator' y'@.
+--
+-- Any real interval contains a unique simplest rational;
+-- in particular, note that @0\/1@ is the simplest rational of all.
+
+-- Implementation details: Here, for simplicity, we assume a closed rational
-- interval. If such an interval includes at least one whole number, then
-- the simplest rational is the absolutely least whole number. Otherwise,
-- the bounds are of the form q%1 + r%d and q%1 + r'%d', where abs r < d
nd'' = simplest' d' r' d r
n'' = numerator nd''
d'' = denominator nd''
-
+#endif