# 3.119 FAQ-693 How to perform Multiple Linear Regression with boundary or constraint?

Last Update: 3/30/2015

Multiple Linear Regression tool in Origin does not support fitting with boundary yet. But as a workaround, you can define a user-defined function with multiple independent variables for nonlinear curve fitting, which allows to put boundaries. such as

 y=(A*x1)+(B*x2)+(C*x3)

To begin with, choose Tools:Fitting Function Builder from the Origin menu to define the function.

Then, set the Bounds and Linear Constrains for the coefficients

Click Finish to create this user defined fitting function.

After fitting done, the results is shown in summary table and can meet the condition of constraint.

Keywords:Linear Curve Fit,Nonlinear Curve Fit, multiple linear regression, boundary, constraint