LFD Book Forum

LFD Book Forum (http://book.caltech.edu/bookforum/index.php)
-   Chapter 3 - The Linear Model (http://book.caltech.edu/bookforum/forumdisplay.php?f=110)
-   -   Assumption in Problem 3.9 (http://book.caltech.edu/bookforum/showthread.php?t=4876)

Fromdusktilldawn 01-22-2019 10:01 PM

Assumption in Problem 3.9
In Problem 3.9, it stated that X^TX is positive definite

Which means it is also invertible

But on page 85, it said that X^TX might not be invertible.

Can someone explain this disparity?

htlin 01-23-2019 02:02 AM

Re: Assumption in Problem 3.9
Problem 3.9 asks you to solve a special case (invertible case) of the more general task (on page 85).

Hope this helps.

All times are GMT -7. The time now is 06:30 AM.

Powered by vBulletin® Version 3.8.3
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
The contents of this forum are to be used ONLY by readers of the Learning From Data book by Yaser S. Abu-Mostafa, Malik Magdon-Ismail, and Hsuan-Tien Lin, and participants in the Learning From Data MOOC by Yaser S. Abu-Mostafa. No part of these contents is to be communicated or made accessible to ANY other person or entity.