NLREG

NLREG is a powerful statistical analysis program that performs linear and nonlinear regression analysis, surface and curve fitting. NLREG determines the values of parameters for an equation, whose form is specified by the user, that cause the equation to best fit a set of data values.

NLREG can handle linear, polynomial, exponential, logistic, periodic, and general nonlinear functions. Unlike many "nonlinear" regression programs that can only handle a limited set of function forms, NLREG can handle essentially any function whose form is specified by user algebraically. NLREG performs statistical regression analysis to estimate the values of parameters for linear, multivariate, polynomial, logistic, exponential, and general nonlinear functions. The regression analysis determines the values of the parameters that cause the function to best fit the observed data that you provide. This process is also called “curve fitting.”

NLREG allows user to specify the function whose parameters are being estimated using ordinary algebraic notation. In addition to determining the parameter estimates, NLREG can be directed to generate an output file with predicted values and residuals. It can also plot the data observations and the computed function.

Although designed for regression analysis, NLREG can also be used to find the root (zero point) or minimum absolute value of a nonlinear expression. DLL (Dynamic Link Library) and COM object versions of NLREG are available for applications that want to call NLREG as an "engine" to perform regressions.

Click here to see an example Visual Basic program that calls the NLREG COM Library. NLREG is in use at hundreds of engineering and research centers around the world. NLREG is in use at hundreds of universities, laboratories, and government agencies around the world (over 20 countries).