nearly_equals,
nearly_ge,
non_very_positive_entries,
- very_positive,
- )
+ very_positive )
where
+
-- | epsilon is the value that will be used in all tests that require
-- some measure of \"closeness.\" Increasing it will make those
-- tests more tolerant.
+ --
epsilon :: Double
epsilon = 0.0001
+
-- | A tiny margin of error.
+--
theta :: Double
theta = 0.0000000000001
+
-- | x almost equals y if x is within 'theta' of y.
+--
+-- Only used in tests.
+--
nearly_equals :: Double -> Double -> Bool
-nearly_equals x y = (abs (x - y)) < theta
+nearly_equals x y =
+ (abs (x - y)) < theta
+
-- | Nearly greater-than or equal-to.
+--
+-- Only used in tests.
+--
nearly_ge :: Double -> Double -> Bool
-x `nearly_ge` y = (x > y) || (x `nearly_equals` y)
+x `nearly_ge` y =
+ (x > y) || (x `nearly_equals` y)
+
-- | x almost equals y if x is within 'epsilon' of y.
+--
+-- Only used in tests.
+--
almost_equals :: Double -> Double -> Bool
-almost_equals x y = (abs (x - y)) < epsilon
+almost_equals x y =
+ (abs (x - y)) < epsilon
infix 4 ~=
(~=) :: Double -> Double -> Bool
-- | Like 'almost_equals', except much more tolerant. The difference
-- between the two arguments must be less than one percent of the sum
-- of their magnitudes.
+--
+-- Only used in tests.
+--
kinda_equals :: Double -> Double -> Bool
kinda_equals x y =
- (abs (x - y)) < threshold
- where
- threshold = ((abs x) + (abs y)) / 100.0
+ (abs (x - y)) < threshold
+ where
+ threshold = ((abs x) + (abs y)) / 100.0
infix 4 ~~=
(~~=) :: Double -> Double -> Bool
-- | x is very positive if it is 'epsilon' greater than zero.
+--
+-- Only used in tests.
+--
very_positive :: Double -> Bool
-very_positive x = x - epsilon > 0
+very_positive x =
+ x - epsilon > 0
-- | Takes a list of 'Double' and returns the ones which are not very
-- positive.
+--
non_very_positive_entries :: [Double] -> [Double]
non_very_positive_entries = filter (not . very_positive)