anchor.diff:  
       /// Element-wise (Hadamard, Schur) product of `a` and `b`
       static member (.*) (a:DM, b:DM) =
  -        let inline ff(a, b) = GlobalConfig.Float32Backend.Mul_Had_M_M(a, b)
  +        let inline ff(a, b) = Backend().Mul_Had_M_M(a, b)
           let inline fd(a, b) = a .* b
           let inline df_da(cp, ap, at) = at .* b
           let inline df_db(cp, bp, bt) = a .* bt
  
positive.code: 
      /// Element-wise addition of `a` and `b`
      static member (+) (a:DM, b:DM) =
          let inline ff(a, b) = GlobalConfig.Float32Backend.Add_M_M(a, b)
          let inline fd(a, b) = a + b
          let inline df_da(cp, ap, at) = at
          let inline df_db(cp, bp, bt) = bt
  
negative.code:             match b with
              | DV(bp)                  -> D(ff(ap, bp))
              | DVF(bp, bt, bi)         -> let cp = fd(a, bp) in DF(cp, df_db(cp, bp, bt), bi)
              | DVR(bp,  _,  _,  _, bi) -> DR(fd(a, bp), ref (D number0), r_c_d(a, b), ref 0u, bi)
          | DVF(ap, at, ai) ->
              match b with
              | DV(_)                   -> let cp = fd(ap, b) in DF(cp, df_da(cp, ap, at), ai)
  