syntax regression model variables

2 次查看（过去 30 天）
Tania
Tania 2014-6-16
评论： Roger Wohlwend 2014-6-18
Hey! Can someone explain me the following syntax:
modelfun=@(b,x)b(1) + b(2)*x(:,1).^b(3)+... b(4)*x(:,2).^b(5); beta0=[-50 500 -1 500 -1]; mdl = fitnlm(ds,modelfun,beta0)
mdl = MPG~ b1 + b2*Horsepower^b3 + b4*Weight^b5
In particular I dont understand: (b,x)- this doesnt take any column of the dataset,right? x(:,1)- does this give me the first column of the dataset? x(:,1)-does this give me the second column of the dataset?
In beta0 I specify then the values of b1, b2 and b4? Or what is it for?
Thanks for your help!

请先登录，再回答此问题。

采纳的回答

Roger Wohlwend
Roger Wohlwend 2014-6-16
The variable modelfun is a function handle and it defines the nonlinear model. Perhaps you should read the Matlab documentation about function handles first before you proceed with the regression. The first part of the handle - @(b,x) - tells matlab that the equation contains two variables: b (the coefficients) and x (the independent variables). Afterwards it shows the model.
Yes, x(:,1) is the first column of the matrix x.
beta0 specifys the inital values for the regression coefficients. Matlab needs them as a starting point for the optimization.
  6 个评论
显示 4更早的评论
Tania
Tania 2014-6-18
Thanks, where can I find gridsearch in the documenation?Thanks!
Roger Wohlwend
Roger Wohlwend 2014-6-18
It is not in the Matlab documentation. I found it in books.

请先登录，再进行评论。

更多回答（0 个）

类别

在 Help Center 和 File Exchange 中查找有关 Nonlinear Regression 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by