anchor.diff:      let rowRange (a:Matrix<_>) = (0,a.NumRows - 1)
       let colRange (a:Matrix<_>) = (0,a.NumCols - 1)
       let wholeRegion a = (colRange a, rowRange a)
  -    let foldByRow f (z:Vector<'T>) (a:matrix) = 
  +    let foldByRow f (z:Vector<'T>) (a:matrix) =
           colRange a |> GU.foldR (fun z j -> MS.mapiV (fun i z -> f z (get a i j)) z) z
  -    let foldByCol f (z:RowVector<'T>) (a:matrix) = 
  +    let foldByCol f (z:RowVector<'T>) (a:matrix) =
           rowRange a |> GU.foldR (fun z i -> MS.mapiRV (fun j z -> f z (get a i j)) z) z
  -    let foldRow f (z:'T) (a:matrix) i = 
  +    let foldRow f (z:'T) (a:matrix) i =
           colRange a |> GU.foldR (fun (z:'T) j -> f z (get a i j)) z
  -    let foldCol f (z:'T) (a:matrix) j = 
  +    let foldCol f (z:'T) (a:matrix) j =
           rowRange a |> GU.foldR (fun (z:'T) i -> f z (get a i j)) z
       let sum (a:matrix)  = MS.sumM a
       let prod (a:matrix)  = MS.prodM a
  
positive.code:     /// [[1.;0.;0.]
      ///  [0.;1.;0.]
      ///  [0.;0.;1.]]
      let identity m : matrix = MG.identity m      
      /// Creates a dense matrix with i rows and j columns. All values are initialized to one (1.).
      let ones m n = create m n 1.0
      /// Returns row of index i of matrix a    
      let getRow (a:matrix) i = MG.getRow a i
      /// Replaces row of index i of matrix a with values of vector v, if vector length matches rowsize
      let setRow (a:Matrix<_>) i (v:Vector<_>) = MG.setRow a i v
  
negative.code: 
      // Accessors
      let get (a:matrix) i j   = MG.get a i j
      let set (a:matrix) i j x = MG.set a i j x
      // Creation
      ///returns a dense matrix with m rows and n rows, applying the init function with the two indices as arguments
      let init  m n f = DS.initDenseMatrixDS  m n f |> MS.dense
      ///returns a dense matrix with the inner lists of the input jagged list as its rows
      let ofJaggedList     xss   = DS.listDenseMatrixDS    xss |> MS.dense
      ///returns a dense matrix with the inner lists of the input jagged list as its columns
  