A Cartesian graph is one which shows numerical relationships by drawing points, lines, curves, or geometric shapes on the Cartesian plane. The Cartesian plane consists of two or more axes joined at a single point called the origin and possibly a grid to help index points on the graph. Numeric indicators should not precede the numbers on the x- and y-axis lines regardless of whether the text is transcribed in literary or Nemeth (mathematics and science) code.
Since the reader is going to graph the equation on this grid (and it seems to fit the definition above), I would not use the numberic indicator on the values shown along the x- and y-axis. If the reader was going to use it to create a scatter plot or a bar graph, I would use the numeric indicator. Since the Guidelines and Standards for Tactile Graphics is still a DRAFT document, and has not yet been approved by BANA, it would not be incorrect (at this point in time) to use the numeric indicator.