Epsilon.hs

-----------------------------------------------------------------------------
-- |
-- Module      :  Linear.Epsilon
-- Copyright   :  (C) 2012 Edward Kmett
-- License     :  BSD-style (see the file LICENSE)
-- Maintainer  :  Edward Kmett <ekmett@gmail.com>
-- Stability   :  provisional
-- Portability :  portable
--
-----------------------------------------------------------------------------
module Linear.Epsilon
  ( Epsilon(..)
  ) where

-- | Provides a fairly subjective test to see if a quantity is near zero.
class Num a => Epsilon a where
  -- | Determine if a quantity is near zero.
  nearZero :: a -> Bool

-- | @'abs' a '<=' 1e-6@
instance Epsilon Float where
  nearZero a = abs a <= 1e-6

-- | @'abs' a '<=' 1e-12@
instance Epsilon Double where
  nearZero a = abs a <= 1e-12