-- | Functions for comparing 'Double' values.
-module Comparisons
+module Comparisons (
+ (~=),
+ (~~=),
+ almost_equals,
+ kinda_equals,
+ nearly_equals,
+ nearly_ge,
+ non_very_positive_entries,
+ very_positive,
+ )
where
-- | epsilon is the value that will be used in all tests that require
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.
+nearly_equals :: Double -> Double -> Bool
+nearly_equals x y = (abs (x - y)) < theta
+
+-- | Nearly greater-than or equal-to.
+nearly_ge :: Double -> Double -> Bool
+x `nearly_ge` y = (x > y) || (x `nearly_equals` y)
-- | x almost equals y if x is within 'epsilon' of y.
almost_equals :: Double -> Double -> Bool