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fossilesque@lemmy.dbzer0.comM to Science Memes@mander.xyzEnglish · 2 months ago

identity theft

lemmy.dbzer0.com

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identity theft

lemmy.dbzer0.com

fossilesque@lemmy.dbzer0.comM to Science Memes@mander.xyzEnglish · 2 months ago
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  • neidu3@sh.itjust.works
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    2 months ago

    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.

    • zqwzzle@lemmy.ca
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      2 months ago

      A square matrix with the ones in the diagonal is called the identity matrix

    • lugal@lemmy.dbzer0.com
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      2 months ago

      It’s an identity matrix. You multiple a vector with it and the result is still the same (identical) vector

    • Gustephan@lemmy.world
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      2 months ago

      Eigen see how this is confusing, I don’t get it either

    • pseudo@jlai.lu
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      1 month ago

      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
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        2 months ago

        Wouldn’t you need to put anyMatrix first, since matrix multiplication isn’t commutative?

        • pseudo@jlai.lu
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          2 months ago

          You are right. I will correct it.

          • fallingcats@discuss.tchncs.de
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            2 months ago

            No I just tried it and I was wrong, it seems like it doesn’t matter for the ID matrix specifically

            • pseudo@jlai.lu
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              2 months 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
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          2 months ago

          Huh? Identity times anyMatrix is also anyMatrix. The matrix just has to have the right dimensions

    • Saleh@feddit.org
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      2 months ago

      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: https://www.geeksforgeeks.org/identity-matrix/

    • ryedaft@sh.itjust.works
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      2 months ago

      It’s like if you multiply or divide by one. Just a bit bigger cuz linear algebra.

  • MichaelScotch@lemmy.world
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    2 months ago

    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
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      2 months ago

      Bernstein bears

    • subtext@lemmy.world
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      2 months ago

      I believe it’s actually, “dude, this is a Wendy’s restaurant.” Check and mate.

      • MichaelScotch@lemmy.world
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        2 months ago

        Well done sir, well done… I mean dude

  • NocturnalMorning@lemmy.world
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    2 months ago

    At least they’re symmetric.

  • pseudo@jlai.lu
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    2 months ago

    Thank you OP!

  • Trollception@sh.itjust.works
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    2 months ago

    Uhh who’s joking about identify theft?

    • Akasazh@feddit.nl
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      2 months ago

      Your username is incredibly apt here

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