NocturnalMorning@lemmy.world
on 15 Mar 19:35
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At least they’re symmetric.
neidu3@sh.itjust.works
on 15 Mar 19:36
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Could one of you scholars please explain the joke for us smoothbrains who don’t get it? All I see is a boolean matrix, and I’m not even sure that is correct.
That 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:
x times 1 is x
anyMatrix times Identity is anyMatrix.
fallingcats@discuss.tchncs.de
on 16 Mar 16:28
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Wouldn’t you need to put anyMatrix first, since matrix multiplication isn’t commutative?
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.
Huh? Identity times anyMatrix is also anyMatrix. The matrix just has to have the right dimensions
MichaelScotch@lemmy.world
on 15 Mar 20:18
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Identity theft is not a joke, Jim. Millions of families suffer every year. Also one that the internet gets wrong all the time: “dude, this is a Wendy’s”, not “sir this is a Wendy’s”
massive_bereavement@fedia.io
on 15 Mar 21:09
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At least they’re symmetric.
Could one of you scholars please explain the joke for us smoothbrains who don’t get it? All I see is a boolean matrix, and I’m not even sure that is correct.
A square matrix with the ones in the diagonal is called the identity matrix
It’s an identity matrix. You multiple a vector with it and the result is still the same (identical) vector
Eigen see how this is confusing, I don’t get it either
You multiply vectors and matrizes row by column.
So for any matrix the fitting identity matrix multiplies each row on the relevant position by one and puts it into a column.
The matrix remains the same.
See example 5 here: www.geeksforgeeks.org/identity-matrix/
That 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:
x times 1 is x anyMatrix times Identity is anyMatrix.
Wouldn’t you need to put
anyMatrixfirst, since matrix multiplication isn’t commutative?You are right. I will correct it.
No I just tried it and I was wrong, it seems like it doesn’t matter for the ID matrix specifically
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.
Huh? Identity times anyMatrix is also anyMatrix. The matrix just has to have the right dimensions
Identity theft is not a joke, Jim. Millions of families suffer every year. Also one that the internet gets wrong all the time: “dude, this is a Wendy’s”, not “sir this is a Wendy’s”
Bernstein bears
I believe it’s actually, “dude, this is a Wendy’s restaurant.” Check and mate.
Well done sir, well done… I mean dude
Uhh who’s joking about identify theft?
Your username is incredibly apt here
Thank you OP!