FIX #4228 (atanh (-1) returns NaN instead of -Infinity)

[ghc-base.git] / GHC / Float.lhs

diff --git a/GHC/Float.lhs b/GHC/Float.lhs
index 9249507..c31be1b 100644 (file)
--- a/GHC/Float.lhs
+++ b/GHC/Float.lhs
@@ -1,5 +1,7 @@
 \begin{code}
 {-# OPTIONS_GHC -XNoImplicitPrelude #-}
+-- We believe we could deorphan this module, by moving lots of things
+-- around, but we haven't got there yet:
 {-# OPTIONS_GHC -fno-warn-orphans #-}
 {-# OPTIONS_HADDOCK hide #-}
 -----------------------------------------------------------------------------
@@ -57,6 +59,11 @@ class  (Fractional a) => Floating a  where
     sinh, cosh, tanh    :: a -> a
     asinh, acosh, atanh :: a -> a
 
+    {-# INLINE (**) #-}
+    {-# INLINE logBase #-}
+    {-# INLINE sqrt #-}
+    {-# INLINE tan #-}
+    {-# INLINE tanh #-}
     x ** y              =  exp (log x * y)
     logBase x y         =  log y / log x
     sqrt x              =  x ** 0.5
@@ -149,19 +156,6 @@ class  (RealFrac a, Floating a) => RealFloat a  where
 %*********************************************************
 
 \begin{code}
-instance Eq Float where
-    (F# x) == (F# y) = x `eqFloat#` y
-
-instance Ord Float where
-    (F# x) `compare` (F# y) | x `ltFloat#` y = LT
-                            | x `eqFloat#` y = EQ
-                            | otherwise      = GT
-
-    (F# x) <  (F# y) = x `ltFloat#`  y
-    (F# x) <= (F# y) = x `leFloat#`  y
-    (F# x) >= (F# y) = x `geFloat#`  y
-    (F# x) >  (F# y) = x `gtFloat#`  y
-
 instance  Num Float  where
     (+)         x y     =  plusFloat x y
     (-)         x y     =  minusFloat x y
@@ -255,7 +249,7 @@ instance  Floating Float  where
 
     asinh x = log (x + sqrt (1.0+x*x))
     acosh x = log (x + (x+1.0) * sqrt ((x-1.0)/(x+1.0)))
-    atanh x = log ((x+1.0) / sqrt (1.0-x*x))
+    atanh x = 0.5 * log ((1.0+x) / (1.0-x))
 
 instance  RealFloat Float  where
     floatRadix _        =  FLT_RADIX        -- from float.h
@@ -293,19 +287,6 @@ instance  Show Float  where
 %*********************************************************
 
 \begin{code}
-instance Eq Double where
-    (D# x) == (D# y) = x ==## y
-
-instance Ord Double where
-    (D# x) `compare` (D# y) | x <## y   = LT
-                            | x ==## y  = EQ
-                            | otherwise = GT
-
-    (D# x) <  (D# y) = x <##  y
-    (D# x) <= (D# y) = x <=## y
-    (D# x) >= (D# y) = x >=## y
-    (D# x) >  (D# y) = x >##  y
-
 instance  Num Double  where
     (+)         x y     =  plusDouble x y
     (-)         x y     =  minusDouble x y
@@ -350,7 +331,7 @@ instance  Floating Double  where
 
     asinh x = log (x + sqrt (1.0+x*x))
     acosh x = log (x + (x+1.0) * sqrt ((x-1.0)/(x+1.0)))
-    atanh x = log ((x+1.0) / sqrt (1.0-x*x))
+    atanh x = 0.5 * log ((1.0+x) / (1.0-x))
 
 {-# RULES "truncate/Double->Int" truncate = double2Int #-}
 instance  RealFrac Double  where