anchor.diff:  
                   let markTime = (float swMark.ElapsedTicks / float Stopwatch.Frequency)
                   let evalTime = (float swEval.ElapsedTicks / float Stopwatch.Frequency)
  -                Log.stop " MarkTime=%.2fs EvalTime=%.2fs" markTime evalTime
  +                //Log.stop " MarkTime=%.2fs EvalTime=%.2fs" markTime evalTime
   
                   totalMarkTime <- totalMarkTime + markTime
                   totalEvalTime <- totalEvalTime + evalTime
  
positive.code:                 let swMark = Stopwatch()
                  let swEval = Stopwatch()
              
                  Log.start "Depth=%-3d StdWidth=%.2f Nodes/Leafs=%-11s" depth stdWidth (sprintf "%d/%d" nodeCount leafCount)
                  for i in 1..runs do
                      if i > 5 then swMark.Start()
                      transact(fun () -> Mod.change root (Trafo3d.Translation(V3d(i, i, i))))
                      if i > 5 then swMark.Stop()
  
                      if i > 5 then swEval.Start()
  
negative.code:                         let subCnt = rnd.Gaussian(0.0, stdWidth)
                          let refine = (abs subCnt) |> int
                          for r in 0..refine do
                              let n = l |> Mod.map (fun x -> x * 2)
                              //let xx = Mod.init Trafo3d.Identity
                              //let n = Mod.map2 (fun a b -> a * b) xx l
                              nextLevel <- nextLevel @ [n]
                              nodeCount <- nodeCount + 1 
                          ()
  