anchor.diff:                  let  ia = FSharp.Collections.ResizeArray<int>()
                   ia.Add(0)
   
  -                for i = 0 to (m - 1) do
  -                    for j = 0 to (n - 1) do
  +                for i = 0 to (length1 - 1) do
  +                    for j = 0 to (length2 - 1) do
                           if (a.Item(i, j)|> System.Convert.ToDouble) >= 0.000001 || (a.Item(i, j)|> System.Convert.ToDouble) <= -0.000001 then
                               ar.Add(a.Item(i, j))
                               ja.Add(j)
                               nnz <- nnz + 1
                       ia.Add(nnz)
  -                SparseRepr (SparseMatrix(opsdata<'T>, ar.ToArray(), ia.ToArray(), n, ja.ToArray()))
  +                SparseRepr (SparseMatrix(opsdata<'T>, ar.ToArray(), ia.ToArray(), length2, ja.ToArray()))
   
           let initSparseM i j x : Matrix<'T> = 
               let opsData = opsdata<'T> 
  
positive.code: 
          let mkDenseMatrixGU ops arr = DenseMatrix(ops,arr)
          let mkSparseMatrixGU ops (arr: 'a[,]) =
              let m = arr |> Array2D.length1
              let n = arr |> Array2D.length2
  
              let mutable nnz = 0
              let  a  = FSharp.Collections.ResizeArray<'a>()
              let  ja = FSharp.Collections.ResizeArray<int>()
              let  ia = FSharp.Collections.ResizeArray<int>()
              ia.Add(0)
              for i = 0 to (m - 1) do
                  for j = 0 to (n - 1) do
                      if ((Array2D.get arr i j) |> System.Convert.ToDouble) >= 0.000001 || ((Array2D.get arr i j)|> System.Convert.ToDouble) <= -0.000001 then
                          a.Add((Array2D.get arr i j))
                          ja.Add(j)
                          nnz <- nnz + 1
                  ia.Add(nnz)
              SparseMatrix(ops, a.ToArray(), ia.ToArray(), n, ja.ToArray())
          let mkRowVecGU ops arr = RowVector(ops, arr)
          let mkVecGU ops arr = Vector(ops,arr)
  
  
negative.code:             match a with 
              | SparseRepr _ -> a
              | DenseRepr a ->
                  let length1 = a.NumRows
                  let length2 = a.NumCols
  
                  let mutable nnz = 0
                  let  ar = FSharp.Collections.ResizeArray<'T>()
  