16.1 Interpolate/Extrapolate

See more related video:Origin VT-0010 Interpolation

Overview

Interpolation/extrapolation is a method of estimating and constructing new data points from a discrete set of known data points. This function generates a uniform linearly spaced interpolated curve by one of four methods: Linear, Cubic Spline, Cubic B-Spline, and Akima Spline.

In Origin, the interpolation tool also supports Apparent Interpolation so it can interpolate data according to current axis settings.

1. Create a new worksheet with input data.
2. Select Analysis: Mathematics: Interpolate/Extrapolate.... This opens interp1XY dialog box.

The dialog box calls the interp1xy X-Function to perform the interpolate/extrapolate calculation.

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. Akima Spline This method is based on a piecewise function composed of a set of polynomials. The Akima interpolation is stable to outliers. Specifies the number of interpolated points. The minimum X value of interpolated curve. The maximum X value of interpolated curve. Boundary condition is only available in Cubic Spline method. Natural 2nd derivatives are 0 on both ends. Not-A-Knot 3rd derivatives are continuous on the second and last-second point. 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 the smoothing and closeness. Larger values will result in smoother curves. Smoothing is only available in Cubic B-Spline method. Spline coefficients when using spline or B-spline method. Available only when the interpolation is performed on a graph. If selected, interpolation is performed using apparent values when the axes scale type has been changed (from linear to log10, for instance). Specifies the output XY data range.

Algorithm

For algorithm details, please refer to Interpolate Extrapolate Y from X.

References

For reference details, please refer to Interpolate/Extrapolate Y from X.