Timeline for Proof of normal equation in regression using tensor notation
Current License: CC BY-SA 3.0
17 events
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| Sep 7, 2020 at 18:13 | answer | added | Gerardo Duran-Martin | timeline score: 2 | |
| Sep 7, 2020 at 17:26 | history | edited | kjetil b halvorsen♦ |
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| Apr 13, 2017 at 12:44 | history | edited | CommunityBot |
replaced http://stats.stackexchange.com/ with https://stats.stackexchange.com/
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| Apr 22, 2015 at 14:13 | history | edited | StasK |
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| May 4, 2014 at 16:39 | comment | added | r_31415 | @cc A matrix is a especial case of a second order tensor. Maybe you're confusing tensors with the idea of tensor notation (using indexes, operations of contraction, etc) | |
| May 4, 2014 at 15:49 | comment | added | caub | @RobertSmith I see the term "partitioned matrices" (still not "tensor") but I guess it's similar | |
| May 4, 2014 at 15:22 | comment | added | r_31415 | @cc Starts in page 4. The propositions that follow are good examples. | |
| May 4, 2014 at 9:41 | comment | added | caub | @RobertSmith in your link page4, I see a Jacobian but no 'tensor' | |
| Apr 2, 2013 at 19:37 | history | edited | r_31415 | CC BY-SA 3.0 |
added clarification in last paragraph
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| Apr 2, 2013 at 16:15 | comment | added | r_31415 | I think the second notation is used to prove the non-intuitive identities of matrix calculus (using the notation without indexes) | |
| Apr 2, 2013 at 14:05 | answer | added | whuber♦ | timeline score: 7 | |
| Apr 2, 2013 at 12:34 | comment | added | whuber♦ | At the beginning, equation (1)--a partially written-out array--, equation (2)--the "$[a_{ij}]$" notation--, and the symbol "$A$" at the end of the subsequent paragraph all refer to the same mathematical object. That's three notations right there. Throughout the rest of the document, the first notation is used rarely (eqs (24) and (67) only) and occasionally in abbreviated (block-matrix) form, as in equation (19); the second notation is almost as rarely used (as in equation (13)); and the third notation--which has no subscripts--is used hundreds of times. | |
| Apr 2, 2013 at 4:38 | comment | added | r_31415 | That is actually true. I don't know what you mean by "the author abandons the multiple-subscript notation for the simpler and clearer vector-matrix notation", though. Which part are you referring to? | |
| Apr 2, 2013 at 4:22 | comment | added | whuber♦ | That document uses at least two notations. Notice how quickly the author abandons the multiple-subscript notation for the simpler and clearer vector-matrix notation. Following that procedure yourself is already pretty good advice--if you get tied up tracking subscripts, you will lose sight of what's really going on. | |
| Apr 2, 2013 at 4:04 | comment | added | r_31415 | I didn't know there are so many conventions. I had in mind something like this: docs.google.com/… in page 4. | |
| Apr 2, 2013 at 4:01 | comment | added | whuber♦ | Offhand I'm familiar with at least a half dozen conventions that could validly be called "tensor notation." One of them is infamously called the "debauch of indices": I hope that's not the one you mean! But what exactly do you want? | |
| Apr 2, 2013 at 3:46 | history | asked | r_31415 | CC BY-SA 3.0 |