anchor.diff:              
                   mean,cov
               | None ->
  +                let k = k  + Expr.diagMat sigmaNs
                   let kInv        = Expr.invert k
                   let kStar      = covMat x xStar
                   let mean = meanXStar + kStar.T .* kInv .* (y - meanX)
  
positive.code:             match pars with
              | LinPars _ -> linearCovariance z z'
              | SEPars parsSE  -> squaredExpCovariance (parsSE.Lengthscale,parsSE.SignalVariance) z z'
          let k           = (covMat x x) + Expr.diagMat sigmaNs
          let kStarstar  = covMat xStar xStar
          
          let meanFct,monotonicity,cut = 
  
negative.code:             let vSUpd = vSUpd |> Expr.checkFinite "vSUpd"
              let tauSite = tauSUpd 
              let vSite =  vSUpd
              let sigma = sigma + (Expr.diagMat (1.0f/tauSite))
              let mu = sigma.*vSite
              sigma,mu,tauSite,vSite
  
          ///Update loop of the EP algorithm runs n iterations
  