16.3 Trace Interpolation

Overview Trace Interpolation is different from ordinary interpolation since it interpolates the curve based on the index of X coordinate rather than adjacent data points in the X coordinate. When the curve is cyclic or periodic, it is more appropriate to use trace interpolation rather than ordinary interpolation. Choose from one of three methods: Linear, Cubic Spline and Cubic B-Spline.

To Perform Trace Interpolation
1. Select Analysis: Mathematics: Trace Interpolate. This opens interp1trace dialog.
2. Specify the Input and desired Method as well as Number of Points.
3. Upon clicking OK, two new columns of interpolated X and Y values are added to the source worksheet.

Dialog Options

Recalculate Controls recalculation of analysis results None Auto Manual For more information, see: Recalculating Analysis Results Specifies the XY range to be interpolated. For help with range controls, see: Specifying Your Input Data Specify the interpolation/extrapolation method. Linear Linear interpolation is a fast method of estimating a data point by constructing a line between two neighboring data points. This method is generally less accurate than more computationally-intensive methods. Cubic Spline This method splits the input data into a given number of pieces, and fits each segment with a cubic polynomial. The second derivative of each cubic function is set equal to zero. With these boundary conditions met, an entire function can be constructed in a piece-wise manner. Cubic B-Spline This method also splits the input data into pieces. each segment is fitted with discrete Bezier splines. The number of interpolated points. Specifies the output XY data range

Algorithm

For more specific information on tool usage or on the specifics of the algorithms used, see the documentation provided for the X-Function interp1trace in the Origin X-Function Help file (Help: X-Functions, or press the F1 key while the dialog box is open).