The Function Organizer tool can be used to create user-defined functions with more than one independent or dependent variable. The NLFit dialog can then be used to fit with such functions. The preview window in the NLFit dialog is capable of plotting only one quantity versus another. However, even if the preview does not "make sense", the fitting process will correctly proceed, once proper data and parameter assignments have been made.
Note that if you wish to fit multiple independent variables with an equation of the type y = A0 + A1 * x1 + A2 * x2 + ...
you can make use of the Multiple Regression tool instead of the nonlinear fitter dialog.
Minimum Origin Version Required: Origin 8.0 SR6
This tutorial will show you how to:
double mix = inhib / ki;act = vm * substr / (km + (1 + mix) * substr);
NOTE: Since we are using OriginC, case must match between defined names and their use in the function definition. e.g. Substr does NOT equal substr.
Click Save and then OK to save the function and close the Organizer.
For more details about User Defined Fitting Function please refer to User Defined Fitting Function using Origin C.