can anybody tell me where I can find the "Differentiation using Savitsky-Golay Smoothing" option in Origin 8. In Origin 6 it was "Analysis:Calculus:Diff/Smooth". But I can't find it in Origin 8.
There is no equivalent in 8, but you can make a template that automates a rough equivalent.
Select your Y data and choose Analysis : Signal Processing : Smoothing Choose the Savitsky-Golay method Pick the number of points (note that Origin 8 limits the smoothing to symmetric number of points = N + 1 + N, so 2 points left and two points right yields 5 points) Pick the boundary condition (new in Origin 8, none similar to 7.5) Pick the Polynomial order Set Recalculate to Auto and click OK
You'll get smoothed XY data in your worksheet.
Select the Smoothed Y column and choose Analysis : Mathematics : Differentiate Enter the derivative order Select Auto for Recalculate and click OK
You'll get the derivative of the smoothed data. This is not an exact match of 7.5 which did this in one step.
If you clear this worksheet and save as a template you can re-import data and the smoothing and derivative will take place automatically.