DataFitX is developed using COM, so it can be used in any. What sets DataFit apart from similar curve fitting and regression programs is its ease of use. NLREG includes a programming language similar to C that you use. Virtually any type of function can be fitted. NLREG fits a mathematical function whose form you specify to a set of data values.
Nonlinear regression - CurveFitter v.4.5.51 CurveFitter performs statistical regression analysis to estimate the values of parameters for linear, multivariate, polynomial, exponential and nonlinear functions.