Adding data points

Generally, the user should aim to keep the number of data points defining a curve to a minimum. Occasionally, however, judicious addition of extra data points may be necessary, for example:

• When too many data points have been permanently deleted

• A straight region needs to be made curved

In a way similar to point removal, data points can be added to a curve graphically or by inserting rows in the table. New data points are initially of type Ordinary.

There are two ways of inserting new data points graphically. This determines the order in which the new points appear in the curve:

• Select the curve itself (by clicking on it with the Left Mouse button). This causes each successive new points to be inserted into the region of the curve that is closest to it.

• Select one of the curve’s existing data points. The first new point will be inserted after this, then the second new point after the first, and so on.

When a curve or a data point is selected, the GEOMETRY \ INSERT DATA POINTS item becomes available. Selecting this causes the cursor to change shape, indicating that the application is in data point insertion mode, . Insert data points by positioning the cursor in any of the orthogonal views and clicking the Left Mouse button.

Figure 3:59. Inserting a data point into the closest region of the curve, having initially selected the curve itself

Figure 3:60. Inserting a sequence of data points, having initially selected an existing data point

A double-click of the Left Mouse button inserts a final data point and exits point insertion mode. The mode can also be exited at any time by deselecting GEOMETRY \ INSERT DATA POINTS or by clicking <Esc>.

Insert data points

1. Select an entire row (corresponding to a data point) by clicking the Left Mouse button on the row header (left-most column).

2. Click the Right Mouse button on the row header and choose INSERT DATAPOINT from the popup menu. A new row is inserted in the table before the selected one. The new data point is positioned halfway along the line that connects its neighbouring points.

Figure 3:61. Using the pop-up menu to insert a data point.