From 01629896e9d5525e2f89c57d1f27d84ec9530365 Mon Sep 17 00:00:00 2001
From: Alex_Hubert <alex.hubert@etu.unistra.fr>
Date: Fri, 22 Oct 2021 15:00:01 +0200
Subject: [PATCH] method : energy Eval

---
 lib/objects.py | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/lib/objects.py b/lib/objects.py
index d757756..cd0dfbd 100755
--- a/lib/objects.py
+++ b/lib/objects.py
@@ -38,7 +38,7 @@ class System:
         coord = coord/self.Mass()
         return coord
 
-    def Lval(self,Lbodylist): #return angular momentum of body in bodylist
+    def Lval(self,Lbodylist): #return angular momentum of bodies in bodylist
         comcoord = np.zeros(3)
         for body in Lbodylist:
             comcoord = comcoord + body.m*body.q
@@ -51,6 +51,17 @@ class System:
             L = L + np.cross(comq[i],body.p)
             i = i+1
         return L
+    def Eval(self,Lbodylist): #return total energy of bodies in bodylist
+        G = 1. #Gravitational constant (here normalized)
+        T = 0
+        W = 0
+        for body in Lbodylist:
+            T = T + 1./2.*body.m*np.linalg.norm(body.v)**2
+            for otherbody in Lbodylist:
+                if body != otherbody:
+                    rij = np.linalg.norm(body.q-otherbody.q)
+                    W = W - G*body.m*otherbody.m/rij
+        return T + W
 
 
 if __name__ == "__main__":