From ed6a0c5bc1082a9d40c317e2313ed9b5046989f6 Mon Sep 17 00:00:00 2001
From: Dimitri Lozeve <dimitri.lozeve@gmail.com>
Date: Thu, 9 Nov 2017 19:47:34 +0000
Subject: [PATCH] Add the updateAll function add the Barnes-Hut threshold
 parameter

---
 app/Main.hs |  8 +++++---
 src/Lib.hs  | 13 +++++++++++++
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/app/Main.hs b/app/Main.hs
index 83454f3..53f68e0 100644
--- a/app/Main.hs
+++ b/app/Main.hs
@@ -64,22 +64,24 @@ csvFromBodies dt bs = concat $ map (csvFromBody dt) bs
 
 -- | Compute all the steps of the simulation
 steps :: Double -- ^ The time step
+  -> Double -- ^ The Barnes-Hut threshold theta
   -> [Body] -- ^ The initial state (list of bodies)
   -> [(Double, [Body])] -- ^ List of successive states with the
                         -- corresponding time
-steps dt b = zip (iterate (dt +) 0) (iterate (updateAll dt) b)
+steps dt theta b = zip (iterate (dt +) 0) (iterate (updateAll dt theta) b)
 
 -- | Show all the steps as CSV
 csvFromInit :: Int -- ^ The number of time steps to keep
   -> Double -- ^ The time step
+  -> Double -- ^ The Barnes-Hut threshold theta
   -> [Body] -- ^ The initial state (list of bodies)
   -> String -- ^ CSV data
-csvFromInit n dt b = concat . take n $ map (uncurry csvFromBodies) (steps dt b)
+csvFromInit n dt theta b = concat . take n $ map (uncurry csvFromBodies) (steps dt theta b)
 
 main :: IO ()
 main = do
   bodies <- replicateM 100 randomBody
-  putStrLn $ csvFromInit 100000 60 bodies
+  putStrLn $ csvFromInit 100000 60 0.5 bodies
 
 {-
 --------------------------------------------------------------------------------
diff --git a/src/Lib.hs b/src/Lib.hs
index 27290b3..0df5dee 100644
--- a/src/Lib.hs
+++ b/src/Lib.hs
@@ -28,6 +28,7 @@ module Lib (
   acceleration,
   -- * Simulation
   update,
+  updateAll,
   -- * Examples
   au, sun, earth, moon, mercury, venus, mars
   ) where
@@ -246,6 +247,18 @@ update dt theta tree (Body name r m pos speed) =
         newpos = pos + dt *^ P newspeed
 
 
+-- | Update all Bodies with a time step dt and a Barnes-Hut threshold
+-- theta
+updateAll :: Double -- ^ The time step
+  -> Double -- ^ The Barnes-Hut threshold theta
+  -> [Body] -- ^ A list of Bodies
+  -> [Body] -- ^ The updated list of Bodies
+updateAll dt theta bs =
+  map (update dt theta tree) bs
+  where tree = buildTree bs
+
+
+
 --------------------------------------------------------------------------------
 -- EXAMPLES
 --------------------------------------------------------------------------------