Most often you construct a contour plot for a table of recorded response values such as the Little Pond data table. In that case, in the launch window, Use Table Data is checked and the Specify Grid button is unavailable. However, if a column has a formula and you specify that column as the response (Y), the Specify Grid button becomes active.

When you click Specify Grid, the window shown in Figure 7.9 appears.

You can complete the Specify Grid window and define the contour grid in any way, regardless of the rows in the existing data table. This feature is also available with table templates that have one or more columns defined by formulas but no rows.