Understanding X–Y data interpolation and extrapolation

Abaqus/CAE performs X–Y data interpolation and extrapolation as necessary when you combine multiple X–Y data objects. You can combine multiple X–Y data objects by using X–Y data operations or by requesting that multiple data objects appear in a single table within an X–Y report.

See Also
Using X–Y data operations
Generating tabular data reports

A complete list of X–Y data operations appears in Using X–Y data operations. Several of the X–Y data operations that accept two or more previously saved X–Y data objects as input arguments require that the data objects have matching X-coordinate values. Examples of such operations are the combine and sum functions.

Similarly, matching X–Y values are required for data objects appearing in the same X–Y report table. For information on combining X–Y data objects into a single report table, see Controlling report layout, width, format, and coordinate system.

If the X-coordinate values to be combined do not match, Abaqus/CAE computes additional data points to allow the objects to be aligned. For each unmatched X-coordinate value, Abaqus/CAE constructs a data pair by creating a matching X-coordinate value and computing a Y-coordinate value as follows:

  • If the missing X-coordinate lies within the minimum and maximum available X-coordinates for the data object, a new Y-coordinate value is computed by linear interpolation.

  • If the missing X-coordinate lies beyond the minimum or maximum available X-coordinates for the data object, a new Y-coordinate value is computed by assuming the Y-coordinate value remains constant beyond these extreme points.

These additional data points exist only to carry out the operation and are not saved as part of the input argument data objects.