From e27eb8abaf99d0016aaa6badffb6568888483c6d Mon Sep 17 00:00:00 2001
From: Iustin Pop <iustin@google.com>
Date: Tue, 17 Nov 2009 02:04:38 +0100
Subject: [PATCH] Specialize the math functions
The statistics functions are currently defined as polymorphic with a
Floating constraint. Changing this to monomorphic on Double type makes
them stricter and much more performant (~70% speedup). This is a cheap
way to recoup some of the loses incurred by the recent proliferation of
metrics.
---
Ganeti/HTools/Utils.hs | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/Ganeti/HTools/Utils.hs b/Ganeti/HTools/Utils.hs
index 9c1dff5bd..66722806f 100644
--- a/Ganeti/HTools/Utils.hs
+++ b/Ganeti/HTools/Utils.hs
@@ -81,11 +81,11 @@ fst3 (a, _, _) = a
-- Simple and slow statistical functions, please replace with better versions
-- | Mean value of a list.
-meanValue :: Floating a => [a] -> a
+meanValue :: [Double] -> Double
meanValue lst = sum lst / fromIntegral (length lst)
-- | Standard deviation.
-stdDev :: Floating a => [a] -> a
+stdDev :: [Double] -> Double
stdDev lst =
let mv = meanValue lst
av = foldl' (\accu em -> let d = em - mv in accu + d * d) 0.0 lst
@@ -93,7 +93,7 @@ stdDev lst =
in bv
-- | Coefficient of variation.
-varianceCoeff :: Floating a => [a] -> a
+varianceCoeff :: [Double] -> Double
varianceCoeff lst = stdDev lst / fromIntegral (length lst)
-- * JSON-related functions
--
GitLab