Comment on identity theft
pseudo@jlai.lu 2 days agoThat matrix of zeros with one in diagonal is called the matrix of identity.
It is famous because when doing multiplication on matrix or vector, it acts likes 1 on “normal” number:
1 times x is x
Identity times anyMatrix is anyMatrix.
fallingcats@discuss.tchncs.de 2 days ago
Wouldn’t you need to put
anyMatrixfirst, since matrix multiplication isn’t commutative?pseudo@jlai.lu 2 days ago
You are right. I will correct it.
fallingcats@discuss.tchncs.de 2 days ago
No I just tried it and I was wrong, it seems like it doesn’t matter for the I’d matrix specifically
pseudo@jlai.lu 2 days ago
I need to freshen up on my linear algebra. I don’t remember on which sense it goes but I think if you swap the factors, you’ll have to you transpose the matrix x to keep the same result.
MBM@lemmings.world 2 days ago
Huh? Identity times anyMatrix is also anyMatrix. The matrix just has to have the right dimensions