The NLFitContext is derived from Analysis class and provide access to the information of the fitting function, as well as the current evaluation state that is generated by implementing the fitting function in Origin C. During non-linear fitting, the fitting function generally will return the corresponding y value for a particular x. However, when convolution and ODE (Ordinary Differential Equation) are involved, the entire curve should be considered, not only for a particular data point. NLFitContext class, which first introduced in Origin 8 SR2, can provide access to the key information with fitter.
For example, if we perform convolution while fitting, NLFitContext can help to monitor the fitted parameters in each iteration. Once they are updated, we can compute the convolution using the Fourier transform. The results can be saved in a defined vector. Then for each x, we can get the evaluated y from the vector with the current data index in NLSFCURRINFO.