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Sample OPJ to download to try: Akima Interpolation.opj
Akima Spline is added as a new data plot line connection method new line connection method, and also added as a new interpolation method.
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To use the Interpolate Gadget, select Gadgets: Interpolate from the Origin menu, when a graph is active
Interpolate/Extrapolate
To use the interpolate/Extrapolate tool, select Analysis: Mathematics: Interpolate/Extrapolate from the Origin menu, when a worksheet or a graph is active
Interpolate/Extrapolate Y from X
To use the interpolate/Extrapolate Y from X tool, select Analysis: Mathematics: Interpolate/Extrapolate Y from X from the Origin menu, when a worksheet is active