diff --git a/Assets/Boids/BoidsNativeArray.cs b/Assets/Boids/BoidsNativeArray.cs
index 1d155dd..b54b56b 100644
--- a/Assets/Boids/BoidsNativeArray.cs
+++ b/Assets/Boids/BoidsNativeArray.cs
@@ -82,7 +82,7 @@ public void Execute(int id) {
                     avgPos += tgtPos;
                 }
             }
-            accel[id] += (avgSpr * weights.x + avgVel * weights.y + avgPos * weights.z) / n;
+            accel[id] += avgSpr / n * weights.x + avgVel / n * weights.y + (avgPos / n - pos) * weights.z;
         }
     }
 
@@ -114,8 +114,8 @@ public void Execute() {
     [SerializeField] protected GameObject prefab;
     [SerializeField] protected Vector3 areaSize;
     [SerializeField] protected float distThreshold;
-    [SerializeField] Vector2 velThreshold;
-    [SerializeField] Vector3 simWeight;
+    [SerializeField] protected Vector2 velThreshold;
+    [SerializeField] protected Vector3 simWeight;
     protected Transform[] objs;
     protected NativeArray<Vector3> pos, vel, acc;
     protected TransformAccessArray trs;
diff --git a/Assets/Boids/BoidsNativeList.cs b/Assets/Boids/BoidsNativeList.cs
index af8251f..124ea3f 100644
--- a/Assets/Boids/BoidsNativeList.cs
+++ b/Assets/Boids/BoidsNativeList.cs
@@ -81,7 +81,8 @@ public void Execute(int id) {
                     avgPos += tgtPos;
                 }
             }
-            accel[id] += (avgSpr * weights.x + avgVel * weights.y + avgPos * weights.z) / n;
+
+            accel[id] += avgSpr / n * weights.x + avgVel / n * weights.y + (avgPos / n - pos) * weights.z;
         }
     }
 
@@ -113,8 +114,8 @@ public void Execute() {
     [SerializeField] protected GameObject prefab;
     [SerializeField] protected Vector3 areaSize;
     [SerializeField] protected float distThreshold;
-    [SerializeField] Vector2 velThreshold;
-    [SerializeField] Vector3 simWeight;
+    [SerializeField] protected Vector2 velThreshold;
+    [SerializeField] protected Vector3 simWeight;
     [SerializeField] KeyCode add = KeyCode.A;
     [SerializeField] KeyCode remove = KeyCode.R;
     protected NativeList<Vector3> pos, vel, acc;
diff --git a/Assets/Boids/Demo.unity b/Assets/Boids/Demo.unity
index e387fc7..31c57ef 100644
--- a/Assets/Boids/Demo.unity
+++ b/Assets/Boids/Demo.unity
@@ -335,10 +335,10 @@ MonoBehaviour:
   m_EditorClassIdentifier: 
   initNum: 10
   prefab: {fileID: 4950830921021070585, guid: 81910fc2cc865994ba8a1da7c3b6a0f6, type: 3}
-  areaSize: {x: 20, y: 20, z: 20}
+  areaSize: {x: 25, y: 25, z: 25}
   distThreshold: 5
   velThreshold: {x: 0, y: 4}
-  simWeight: {x: 8, y: 6, z: 1}
+  simWeight: {x: 4, y: 0.8, z: 0.3}
   add: 97
   remove: 114
 --- !u!4 &1361161912
@@ -400,7 +400,7 @@ MonoBehaviour:
   m_EditorClassIdentifier: 
   num: 3000
   prefab: {fileID: 4950830921021070585, guid: 81910fc2cc865994ba8a1da7c3b6a0f6, type: 3}
-  areaSize: {x: 20, y: 20, z: 20}
+  areaSize: {x: 25, y: 25, z: 25}
   distThreshold: 5
   velThreshold: {x: 0, y: 4}
-  simWeight: {x: 8, y: 6, z: 1}
+  simWeight: {x: 4, y: 0.8, z: 0.3}
diff --git a/Packages/manifest.json b/Packages/manifest.json
index d8dbe3a..d65ff0b 100644
--- a/Packages/manifest.json
+++ b/Packages/manifest.json
@@ -1,13 +1,13 @@
 {
   "dependencies": {
-    "com.unity.burst": "1.1.2",
+    "com.unity.burst": "1.3.0-preview.10",
     "com.unity.collab-proxy": "1.2.16",
     "com.unity.ext.nunit": "1.0.0",
-    "com.unity.ide.rider": "1.1.0",
-    "com.unity.ide.vscode": "1.1.3",
-    "com.unity.jobs": "0.2.1-preview.3",
+    "com.unity.ide.rider": "1.1.4",
+    "com.unity.ide.vscode": "1.1.4",
+    "com.unity.jobs": "0.2.9-preview.15",
     "com.unity.mathematics": "1.1.0",
-    "com.unity.test-framework": "1.1.3",
+    "com.unity.test-framework": "1.1.13",
     "com.unity.textmeshpro": "2.0.1",
     "com.unity.timeline": "1.2.6",
     "com.unity.ugui": "1.0.0",
diff --git a/ProjectSettings/ProjectVersion.txt b/ProjectSettings/ProjectVersion.txt
index 9b0e50b..c7d3fa9 100644
--- a/ProjectSettings/ProjectVersion.txt
+++ b/ProjectSettings/ProjectVersion.txt
@@ -1,2 +1,2 @@
-m_EditorVersion: 2019.3.0f1
-m_EditorVersionWithRevision: 2019.3.0f1 (ffacea4b84e7)
+m_EditorVersion: 2019.3.11f1
+m_EditorVersionWithRevision: 2019.3.11f1 (ceef2d848e70)