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Curve Fitting

There are 8 types of functions available to the user to fit the data.

Example

Let us now make a curve fitting with the scatter plot from the previous section.

Click on the Curve fitting tab to display the configurations:

curve-fitting-1.png curve-fitting-1-dark.png

Trace (Legend): the traces (legends) are automatically loaded as options, select a trace that you want to fit.

Fit equations: choose one of those equations below to fit.

  • 1st order: \(y = A + Bx\)
  • 2nd order: \(y = A + Bx + Cx^2\)
  • 3rd order: \(y = A + Bx + Cx^2 + Dx^3\)
  • 4th order: \(y = A + Bx + Cx^2 + Dx^3 + Ex^4\)
  • 5th order: \(y = A + Bx + Cx^2 + Dx^3 + Ex^4 + Fx^5\)
  • 6th order: \(y = A + Bx + Cx^2 + Dx^3 + Ex^4 + Fx^5 + Gx^6\)
  • Theil-Sen regression (robust 1st order): \(y = A + Bx\) (Robust)
  • VFT: \(\log_{10}y = A + B/(x - C)\)

x ranges: the min/max x values are automatically set when trace is selected. You can manually modify the ranges after.

Fitting result: the fitting result (equation) or any messages are displayed here.

Again, let's use the trace GNo: 20006 as an example, and since we already know that we are dealing with viscosity data, we choose the equation VFT for fitting.

curve-fitting-2.png curve-fitting-2-dark.png

Click on Run to perform the fitting.

curve-fitting-3.png curve-fitting-3-dark.png

Show only the legend "GNo: 20006" and the legend "Fit of GNo: 20006": curve-fitting-4.png curve-fitting-4-dark.png

You can copy the equations for use in other applications such as Excel.

Info

We are also seeking for other good equations (models) like the Adam Gibbs equation to make better prediction (fitting). Please contact us if you know how or would like to help.