Mantis#1778. Thank you kindly, Junta_Kohime for a patch that:

llRot2Left and llRot2Up functions modified, using fast algebric 
calculations instead of vectors and quaternions products. 
The accuracy is the same. Normalization is now implemented.

1 files changed, 30 insertions, 2 deletions

diff --git a/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/LSL_Api.cs b/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/LSL_Api.cs
index e396bb4..decd2d0 100644
--- a/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/LSL_Api.cs
+++ b/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/LSL_Api.cs
@@ -437,13 +437,41 @@ namespace OpenSim.Region.ScriptEngine.Shared.Api
         public LSL_Types.Vector3 llRot2Left(LSL_Types.Quaternion r)
         {
             m_host.AddScriptLPS(1);
-            return (new LSL_Types.Vector3(0, 1, 0) * r);
+            double x,y,z,m;
+            m = Math.Sqrt(r.x*r.x+r.y*r.y+r.z*r.z+r.s*r.s);
+            // m is always greater than zero
+            if (m!=1) // if m is not equal to 1 then Rotation needs to be normalized
+            {
+                r.x/=m;
+                r.y/=m;
+                r.z/=m;
+                r.s/=m;
+            }
+            // Fast Algebric Calculations instead of Vectors & Quaternions Product
+            x = 2*(r.x*r.y-r.z*r.s);
+            y = -r.x*r.x+r.y*r.y-r.z*r.z+r.s*r.s;
+            z = 2*(r.x*r.s+r.y*r.z);
+            return (new LSL_Types.Vector3(x,y,z)); 
         }
 
         public LSL_Types.Vector3 llRot2Up(LSL_Types.Quaternion r)
         {
             m_host.AddScriptLPS(1);
-            return (new LSL_Types.Vector3(0, 0, 1) * r);
+            double x,y,z,m;
+            m = Math.Sqrt(r.x*r.x+r.y*r.y+r.z*r.z+r.s*r.s);
+            // m is always greater than zero
+            if (m!=1) // if m is not equal to 1 then Rotation needs to be normalized
+            {
+                r.x/=m;
+                r.y/=m;
+                r.z/=m;
+                r.s/=m;
+            }
+            // Fast Algebric Calculations instead of Vectors & Quaternions Product
+            x = 2*(r.x*r.z+r.y*r.s);
+            y = 2*(-r.x*r.s+r.y*r.z);
+            z = -r.x*r.x-r.y*r.y+r.z*r.z+r.s*r.s;
+            return (new LSL_Types.Vector3(x,y,z));
         }
 
         public LSL_Types.Quaternion llRotBetween(LSL_Types.Vector3 a, LSL_Types.Vector3 b)