From 851ccb5520035c38a8c2103e9569c4b302aa7d80 Mon Sep 17 00:00:00 2001
From: Nick Bowler <nbowler@draconx.ca>
Date: Fri, 19 Feb 2010 17:38:44 -0500
Subject: [PATCH] floating: Add scalb as the altfloat version of scalbln.

I don't think this function is really useful in the context of
manipulating the floating point environmnent, so it is in the
PrimFloat class.  Move logb down there too, since they're a pair.
---
 Data/Floating/Classes.hs      | 8 +++++---
 Data/Floating/Environment.hs  | 1 -
 Data/Floating/Types/Double.hs | 3 ++-
 Data/Floating/Types/Float.hs  | 3 ++-
 4 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/Data/Floating/Classes.hs b/Data/Floating/Classes.hs
index 4c67026..b72a795 100644
--- a/Data/Floating/Classes.hs
+++ b/Data/Floating/Classes.hs
@@ -101,9 +101,6 @@ class Floating a => RealFloat a where
     log1p     :: a -> a
     -- | Base-2 logarithm function.
     log2      :: a -> a
-    -- | Extracts the exponent of a floating point value.  If the value is
-    -- subnormal, the result is as if the value were normalized.
-    logb      :: a -> a
     -- | Error function.
     erf       :: a -> a
     -- | Complementary error function.
@@ -138,3 +135,8 @@ class (Roundable a, RealFloat a) => PrimFloat a where
     -- floating point number.
     floatRange     :: Num b => a -> (b, b)
     classify       :: a -> FPClassification
+    -- | Extracts the exponent of a floating point value.  If the value is
+    -- subnormal, the result is as if the value were normalized.
+    logb           :: a -> a
+    -- | Scales a floating point value by an integral power of the radix.
+    scalb          :: Integral b => a -> b -> a
diff --git a/Data/Floating/Environment.hs b/Data/Floating/Environment.hs
index 8dc41b6..7aea8e6 100644
--- a/Data/Floating/Environment.hs
+++ b/Data/Floating/Environment.hs
@@ -180,7 +180,6 @@ instance RealFloat a => RealFloat (FEnv a) where
     log10     = liftA  log10
     log1p     = liftA  log1p
     log2      = liftA  log2
-    logb      = liftA  logb
     erf       = liftA  erf
     erfc      = liftA  erfc
     gamma     = liftA  gamma
diff --git a/Data/Floating/Types/Double.hs b/Data/Floating/Types/Double.hs
index cc6e3b1..a27b52b 100644
--- a/Data/Floating/Types/Double.hs
+++ b/Data/Floating/Types/Double.hs
@@ -152,7 +152,6 @@ instance RealFloat Double where
     log10     = libmDouble  c_log10
     log1p     = libmDouble  c_log1p
     log2      = libmDouble  c_log2
-    logb      = libmDouble  c_logb
     erf       = libmDouble  c_erf
     erfc      = libmDouble  c_erfc
     gamma     = libmDouble  c_tgamma
@@ -165,3 +164,5 @@ instance PrimFloat Double where
     floatPrecision = const DBL_MANT_DIG_VAL
     floatRange     = const (DBL_MIN_EXP_VAL, DBL_MAX_EXP_VAL)
     classify       = toEnum . fromIntegral . double_classify . toFloating
+    logb           = libmDouble c_logb
+    scalb x e      = toFloating $ c_scalbln (toFloating x) (fromIntegral e)
diff --git a/Data/Floating/Types/Float.hs b/Data/Floating/Types/Float.hs
index b8c1f66..101d005 100644
--- a/Data/Floating/Types/Float.hs
+++ b/Data/Floating/Types/Float.hs
@@ -148,7 +148,6 @@ instance RealFloat Float where
     log10     = libmFloat  c_log10f
     log1p     = libmFloat  c_log1pf
     log2      = libmFloat  c_log2f
-    logb      = libmFloat  c_logbf
     erf       = libmFloat  c_erff
     erfc      = libmFloat  c_erfcf
     gamma     = libmFloat  c_tgammaf
@@ -161,3 +160,5 @@ instance PrimFloat Float where
     floatPrecision = const FLT_MANT_DIG_VAL
     floatRange     = const (FLT_MIN_EXP_VAL, FLT_MAX_EXP_VAL)
     classify       = toEnum . fromIntegral . float_classify . toFloating
+    logb           = libmFloat c_logbf
+    scalb x e      = toFloating $ c_scalblnf (toFloating x) (fromIntegral e)
-- 
2.11.4.GIT