diff --git a/OpenSim/Framework/Servers/HttpServer/OSHttpServer/HttpInputItem.cs b/OpenSim/Framework/Servers/HttpServer/OSHttpServer/HttpInputItem.cs
index 2a3fb37dfb..8ca7cde52b 100644
--- a/OpenSim/Framework/Servers/HttpServer/OSHttpServer/HttpInputItem.cs
+++ b/OpenSim/Framework/Servers/HttpServer/OSHttpServer/HttpInputItem.cs
@@ -71,8 +71,9 @@ namespace OSHttpServer
         /// <returns><see cref="HttpInputItem.Empty"/> if no item was found.</returns>
         public HttpInputItem this[string name]
         {
-            get {
-                return _items.ContainsKey(name) ? _items[name] : Empty;
+            get
+            {
+                return _items.TryGetValue(name, out HttpInputItem hii) ? hii : Empty;
             }
         }
 
@@ -144,7 +145,7 @@ namespace OSHttpServer
         /// <returns>true if the sub-item exists and has a value; otherwise false.</returns>
         public bool Contains(string name)
         {
-            return _items.ContainsKey(name) && _items[name].Value != null;
+            return _items.TryGetValue(name, out HttpInputItem hii) && hii.Value != null;
         }
 
         /// <summary> Returns a formatted representation of the instance with the values of all contained parameters </summary>
@@ -216,7 +217,7 @@ namespace OSHttpServer
         {
             get 
             {
-                return _items.ContainsKey(name) ? _items[name] : Empty;
+                return _items.TryGetValue(name, out HttpInputItem hii) ? hii : Empty;
             }
         }
 
diff --git a/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/LSL_Api.cs b/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/LSL_Api.cs
index 0b3134a7f6..d53bb8d653 100644
--- a/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/LSL_Api.cs
+++ b/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/LSL_Api.cs
@@ -833,9 +833,9 @@ namespace OpenSim.Region.ScriptEngine.Shared.Api
             return Math.Tan(f);
         }
 
-        public LSL_Float llAtan2(LSL_Float x, LSL_Float y)
+        public LSL_Float llAtan2(LSL_Float y, LSL_Float x)
         {
-            return Math.Atan2(x, y);
+            return Math.Atan2(y, x);
         }
 
         public LSL_Float llSqrt(double f)
diff --git a/OpenSim/Region/ScriptEngine/Shared/Api/Interface/ILSL_Api.cs b/OpenSim/Region/ScriptEngine/Shared/Api/Interface/ILSL_Api.cs
index fb6f2c58ff..325f342e0e 100644
--- a/OpenSim/Region/ScriptEngine/Shared/Api/Interface/ILSL_Api.cs
+++ b/OpenSim/Region/ScriptEngine/Shared/Api/Interface/ILSL_Api.cs
@@ -43,7 +43,9 @@ namespace OpenSim.Region.ScriptEngine.Shared.Api.Interfaces
     {
         void state(string newState);
 
+                   //ApiDesc Returns absolute version as val (ie as postive value)
        LSL_Integer llAbs(LSL_Integer val);
+                   //ApiDesc Returns cosine of val (val in radians)
          LSL_Float llAcos(LSL_Float val);
                    //ApiDesc Sleep 0.1
               void llAddToLandBanList(LSL_Key avatarId, LSL_Float hours);
@@ -55,8 +57,10 @@ namespace OpenSim.Region.ScriptEngine.Shared.Api.Interfaces
          LSL_Float llAngleBetween(LSL_Rotation a, LSL_Rotation b);
               void llApplyImpulse(LSL_Vector force, LSL_Integer local);
               void llApplyRotationalImpulse(LSL_Vector force, int local);
+                   //ApiDesc Returns sine of val (val in radians)
          LSL_Float llAsin(LSL_Float val);
-         LSL_Float llAtan2(LSL_Float x, LSL_Float y);
+                   //ApiDesc Returns the angle whose tangent is the y/x
+         LSL_Float llAtan2(LSL_Float y, LSL_Float x);
               void llAttachToAvatar(LSL_Integer attachment);
               void llAttachToAvatarTemp(LSL_Integer attachmentPoint);
            LSL_Key llAvatarOnSitTarget();
diff --git a/OpenSim/Region/ScriptEngine/Shared/Api/Runtime/LSL_Stub.cs b/OpenSim/Region/ScriptEngine/Shared/Api/Runtime/LSL_Stub.cs
index ccda2911f4..41effdfec5 100644
--- a/OpenSim/Region/ScriptEngine/Shared/Api/Runtime/LSL_Stub.cs
+++ b/OpenSim/Region/ScriptEngine/Shared/Api/Runtime/LSL_Stub.cs
@@ -123,9 +123,9 @@ namespace OpenSim.Region.ScriptEngine.Shared.ScriptBase
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public LSL_Float llAtan2(LSL_Float x, LSL_Float y)
+        public LSL_Float llAtan2(LSL_Float y, LSL_Float x)
         {
-            return m_LSL_Functions.llAtan2(x, y);
+            return m_LSL_Functions.llAtan2(y, x);
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]