Initial commit

Core is taken from  statistcs test suite

.hgignore

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+dist

LICENSE

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+Copyright (c) Aleksey Khudyakov
+
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions
+are met:
+
+1. Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright
+   notice, this list of conditions and the following disclaimer in the
+   documentation and/or other materials provided with the distribution.
+
+3. Neither the name of the author nor the names of his contributors
+   may be used to endorse or promote products derived from this software
+   without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS ``AS IS'' AND ANY EXPRESS
+OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE FOR
+ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.

Setup.hs

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+import Distribution.Simple
+main = defaultMain

Test/QuickCheck/Numeric.hs

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+-- | Helper for writing tests for numeric code
+module Test.QuickCheck.Numeric (
+    -- * Approximate equality
+    eq
+  , eqC
+    -- * Function monotonicity
+  , Monotonicity(..)
+  , monotonicFunction
+  , monotonicFunctionIEEE
+  ) where
+
+import Data.Complex
+import qualified Numeric.IEEE    as IEEE
+
+
+
+
+----------------------------------------------------------------
+-- Approximate equality
+----------------------------------------------------------------
+
+-- | Approximate equality for 'Double'. Doesn't work well for numbers
+--   which are almost zero.
+eq :: Double                    -- ^ Relative error
+   -> Double -> Double -> Bool
+eq eps a b 
+  | a == 0 && b == 0 = True
+  | otherwise        = abs (a - b) <= eps * max (abs a) (abs b)
+
+-- | Approximate equality for 'Complex Double'
+eqC :: Double                   -- ^ Relative error
+    -> Complex Double
+    -> Complex Double
+    -> Bool
+eqC eps a@(ar :+ ai) b@(br :+ bi)
+  | a == 0 && b == 0 = True
+  | otherwise        = abs (ar - br) <= eps * d
+                    && abs (ai - bi) <= eps * d
+  where
+    d = max (realPart $ abs a) (realPart $ abs b)
+
+
+
+----------------------------------------------------------------
+-- Function monotonicity
+----------------------------------------------------------------
+
+-- | Function monotonicity type.
+data Monotonicity
+  = StrictInc   -- ^ Strictly increasing function
+  | MonotoneInc -- ^ Monotonically increasing function
+  | StrictDec   -- ^ Strictly decreasing function
+  | MonotoneDec -- ^ Monotonically decreasing function
+  deriving (Show,Eq,Ord)
+
+
+-- | Check that function is nondecreasing. For floating point number
+--   it may give spurious failures so 'monotonicFunction'
+--   should be used in this case.
+monotonicFunction :: (Ord a, Ord b) => Monotonicity -> (a -> b) -> a -> a -> Bool
+monotonicFunction cmp f x1 x2
+  = f (min x1 x2) `op` f (max x1 x2)
+  where
+    op = case cmp of
+           StrictInc   -> (< )
+           MonotoneInc -> (<=)
+           StrictDec   -> (> )
+           MonotoneDec -> (>=)
+
+-- | Check that function is nondecreasing taking rounding errors into
+--   account. This function makes no distinction between strictly
+--   increasing function and monotonically increasing function since
+--   distinction is pointless for floating point.
+--
+--   In fact funstion is allowed to decrease less than one ulp in order
+--   to guard againist problems with excess precision. On x86 FPU works
+--   with 80-bit numbers but doubles are 64-bit so rounding happens
+--   whenever values are moved from registers to memory
+monotonicFunctionIEEE :: (Ord a, IEEE.IEEE b) => Monotonicity -> (a -> b) -> a -> a -> Bool
+monotonicFunctionIEEE cmp f x1 x2
+  =  y1 `op` y2
+  || abs (y1 - y2) < abs (y2 * IEEE.epsilon)
+  where
+    y1 = f (min x1 x2)
+    y2 = f (max x1 x2)
+    op = case cmp of
+           StrictInc   -> (<=)
+           MonotoneInc -> (<=)
+           StrictDec   -> (>=)
+           MonotoneDec -> (>=)

quickcheck-numeric.cabal

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+Name:           quickcheck-numeric
+Version:        0.1
+Synopsis:       Helpers for writing tests for numeric code
+Description:
+  Helpers for writing tests for numeric code
+
+Cabal-Version:  >= 1.6
+License:        BSD3
+License-File:   LICENSE
+Author:         Aleksey Khudyakov <alexey.skladnoy@gmail.com>
+Maintainer:     Aleksey Khudyakov <alexey.skladnoy@gmail.com>
+Homepage:       http://bitbucket.org/Shimuuar/quickcheck-numeric
+Category:       Data
+Build-Type:     Simple
+
+source-repository head
+  type:     hg
+  location: http://bitbucket.org/Shimuuar/quickcheck-numeric
+
+Library
+  Ghc-options:          -Wall
+  Build-Depends:
+    base    >=3 && <5,
+    ieee754 >= 0.7.3
+  Exposed-modules:      
+    Test.QuickCheck.Numeric