anchor.diff:  
   %% API
   -export([new/4,
  +         ones/3,
  +         zeros/3,
  +         eye/3,
            is_square/1,
   
            get/3,
  
positive.code:       };
  new(_, _, _, _) ->
      throw(error_bad_length).
  
  %% @doc True if the matrix is square, false otherwise.
  -spec is_square(#matrix{}) -> boolean().
  
negative.code:     unit = Unit,
      data = <<Pre/bits, Value:Unit, Suf/bits>>
    }.
  
  %% @doc Transpose of matrix
  -spec transpose(#matrix{}) -> #matrix{}.
  