11.9 The Interpolate Gadget

Specify the X data range for the ROI.

From

The beginning X scale value.

To

The ending X scale value.

Fixed (Prevent moving by ROI)

Fix the X scale to prevent rescaling when moving the ROI box.

Show Tool Name

Specify whether to show the tool's name near the top of the ROI.

Fill Color

Specify the ROI fill color.

Interpolation Line Color

Specify the color of the interpolation line.

Interpolation Line Width

Specify the width of the interpolation line.

Y at Left

The Y value that corresponds to the left edge of the ROI.

Y at Right

The Y value that corresponds to the right edge of the ROI.

Y at Specified X

The Y value that corresponds to an X value which you specify in the X edit box.

X

This edit box is available only when the Y at Specified X check box is checked.

Specifies the interpolation/extrapolation method. Options include:

• Linear

  Linear interpolation is a fast method of estimating a data point by constructing a line between two neighboring data points.

• 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.

• Akima Spline

  This method is based on a piecewise function composed of a set of polynomials. The akima interpolation is stable to outliers.

Please see the algorithm here.

Number of Points

Specify the number of interpolation/extrapolation points.

Boundary

Boundary condition is available when Method is Cubic Spline. Options include:

• Natural

  The 2nd derivatives are 0 on both ends.

• Not-A-Knot

  The 3rd derivatives are continuous on the second and last-second point.

Smoothing Factor

Available when Method is Cubic B-Spline. A non-negative parameter that specifies the smoothness of the interpolated curve in Cubic B-Spline interpolation. The factor helps user control the balance between smoothing and fidelity to the actual data. Larger values will result in smoother curves.

Fit Limits To

Specify the interpolation curve boundary.

• Interpolate to Rectangle Edge

  Interpolate to the ROI edges. If the ROI range is larger than the source data range, the interpolation will stop at the edge of the source data.

• Interpolate/Extrapolate to Rectangle Edge

  Interpolate/Extrapolate to the ROI edges, regardless of the source data range.

• Data Points

  Interpolate between the specified data points, which are enclosed by the ROI rectangle.

• Interpolate/Extrapolate to Full Axis Edge

  Interpolate/Extrapolate to the full X axis scale range in the input graph, regardless of the source data range.

• Custom

  Interpolate/Extrapolate to a customized data range, specified by the Left and Right value.

• When you generate new output, results are output to [%H-Interpolate]Result by default (here %H means the Short Name of source graph), but other books and sheets can be specified. If the book and sheet do not exist, they will be created on output.
• Alternately, you can click the flyout button to the right of Result Worksheet Name and choose Sheet in Input Book. This fills the edit box with [<input>]Result. When you generate new output, results are output to a sheet named Result in the source book.

• By default, Auto mode is enabled. When Auto is enabled, plot selection is controlled by clicking on a plot in the graph window or Object Manager. Prior to Origin 2019, Origin did not support Auto; to change target plot/data in older versions, you must select a plot from the fly-out menu.
• Place a check mark in front of any plot to select that plot.
• Click Select... or More ... to open the Select Plot(s) dialog and change selection.