What did he mean by this?

What did he mean by this?

  1. 2 weeks ago
    Anonymous

    There is a Wikipedia page about Carmack fast inverse root square, seriously.

    • 2 weeks ago
      Anonymous

      >Carmack
      Not due to Carmack.

    • 2 weeks ago
      Anonymous

      >Carmack
      not his

      Back when engineers had knowledge in maths and not in Indian tutorials.

      >when engineers had knowledge in maths
      they literally took it from an academic paper

      • 2 weeks ago
        Anonymous

        >they literally took it from an academic paper
        You need knowledge in maths to know:
        -What you're looking for
        -Where to look for
        -How to read an academic paper

        Modern software engineers will get grumpy if they can't find the solution on stackoverflow, you can't expect them to waste time looking for academic papers and reading them.

        • 2 weeks ago
          Anonymous

          Too much projection

          • 2 weeks ago
            Anonymous

            [log in to view media]

            >t.

            • 2 weeks ago
              Anonymous

              [log in to view media]

              Fantastic posts

    • 2 weeks ago
      Anonymous

      He stole it from an algo book thays why it has the what the fuck. He cant math.
      1. Convert float to long to enable bit shift 2 division
      2. Make initial guess with help of logarithms and a magic number
      3. One step Newtons algorithm

  2. 2 weeks ago
    Anonymous

    Back when engineers had knowledge in maths and not in Indian tutorials.

    • 2 weeks ago
      Anonymous

      Engineers have knowledge in maths today too, you are inside a meme bubble.

      • 2 weeks ago
        Anonymous

        "Software engineers" have knowledge in maths?

        • 2 weeks ago
          Anonymous

          I do and I'm sure I'm not alone
          There were math courses at my uni
          Calc 1, 2
          Linear algebra 1,2
          Operation research
          Logic and algebraic structures

          • 2 weeks ago
            Anonymous

            >Calc 1, 2
            >Linear algebra 1,2
            >Operation research
            >Logic and algebraic structures
            That last one might be real math. But probably not. How far into Romans linear algebra before you're out of your depth

            • 2 weeks ago
              Anonymous

              Are you one of those retards who think math is only about algebraic structures?

              • 2 weeks ago
                Anonymous

                math is partly about algebraic structures and i hate that computational calc (read as heat) is ignored

              • 2 weeks ago
                Anonymous

                Are you one of those retards who think calculus and linear algebra are areas of active research?

              • 2 weeks ago
                Anonymous

                You're retarded
                Calc is actively researched and so is linear algebra.
                Some SVD results were from the 60's and it had an enormous impact in various fields (eg subspace identification and data mining/information retrieval) which is more or less the same time NN "came out"
                Linear algebra is a tremendous tool for real problem and a huge amount of filed can benefit from researching

          • 2 weeks ago
            Anonymous

            is this about the average maths knowledge for CS grads? I have a bachelor's in economics and we got up to measure theory/functional analysis/PDEs. Looking to learn2code, but I keep getting the impression I should do so self taught.

            • 2 weeks ago
              Anonymous

              I don't know what the average is.
              Functional analysis and pde were addressed in calc 2 and partially in control theory, model identification and adaptive control/identification

      • 2 weeks ago
        Anonymous

        Having memorized some formulas is different from actually understand what it does and why it exists.

        • 2 weeks ago
          Anonymous

          I can tell you've never taken any math at a university level.

    • 2 weeks ago
      Anonymous

      *tensorflow blog posts etc.

    • 2 weeks ago
      Anonymous

      Mathematicians wouldn't touch this

    • 2 weeks ago
      Anonymous

      >gamedev copypasted code from somebody smarter than him
      Those were the times.

  3. 2 weeks ago
    bruce3434

    In Rust this is just
    fn quake_rsqrt(number: f32) -> f32 {
    let mut i: i32 = number.to_bits() as i32;
    i = 0x5F375A86_i32.wrapping_sub(i / 2);
    let y = f32::from_bits(i as u32);
    y * (1.5 - (number * 0.5 * y * y))
    }

    No magic, no autism.

    • 2 weeks ago
      Anonymous

      >No magic
      >No autism
      >Leaves the most magical, autistic part.

      • 2 weeks ago
        bruce3434

        ??
        I removed the undefined behavior.

        • 2 weeks ago
          Anonymous

          >0x5F375A86
          The fuck is this for?

          • 2 weeks ago
            bruce3434

            http://www.lomont.org/papers/2003/InvSqrt.pdf
            Are you implying carmack invented this formula?

            • 2 weeks ago
              Anonymous

              No, she's saying that the formula is the magic autistic part, not the (now-UB) pointer-assisted type punning
              She didn't even bring up Carmack

              • 2 weeks ago
                bruce3434

                >No, she's saying that the formula is the magic autistic part,
                It's not, it's an implementation of Newton's approximation.
                > I just don't understand where that part comes from
                Read the paper. You should have been taught this in your year 12.

              • 2 weeks ago
                Anonymous

                >It's not, it's an implementation of Newton's approximation.
                I know Newton's approximation, but any code that depends on the bitwise representation of floating point is magical and autistic in my book, except maybe if it clearly labels and decomposes sign and mantissa and so on.
                (I may have misunderstood how broadly you meant "formula".)

            • 2 weeks ago
              Anonymous

              >Are you implying carmack invented this formula?
              What? No, how did you reach that conclusion? I just don't understand where that part comes from, and is easily the most magical part. Bit hacking and newtons method aren't mysterious, but that magic number... what is is? Where did ti come from?

        • 2 weeks ago
          Anonymous

          >I removed the undefined behavior
          And yet it was used in production. It's basically impossible to write C without "undefined behavior". I can't think of a single compiler or platform which would fail to produce the desired result

      • 2 weeks ago
        Anonymous

        No magic, no autism, 100% female hormones.

        >ORANGE CRAB BAD MUH HECKIN THREEHALFS CONSTANT IS HECKIN MAGICAL

    • 2 weeks ago
      Anonymous

      and?

    • 2 weeks ago
      Anonymous

      No magic, no autism, 100% female hormones.

      • 2 weeks ago
        bruce3434

        Why do whitoids turn everything about homosexualry?

        • 2 weeks ago
          Anonymous

          cool it with the antisemetic remarks brucella

    • 2 weeks ago
      Anonymous

      Like most rust rewrites, this one excludes critical functionality. Reread the Rust ABI if you think this will actually work.

      • 2 weeks ago
        Anonymous

        nah

      • 2 weeks ago
        bruce3434

        What ABI? You don’t know what you’re talking about.

        https://doc.rust-lang.org/rust-by-example/fn.html

        what a fucking mess of a language. I kind of played along with all the rust memes on this board, but dear lord is it a piece of shit.

        Where’s the mess?

        Just look how clueless rustniles are, this is not even need nowdays, there are intrinsics for this you know.

        When did I say there’s a need for it? Are you seeing things?

    • 2 weeks ago
      Anonymous

      https://doc.rust-lang.org/rust-by-example/fn.html

      what a fucking mess of a language. I kind of played along with all the rust memes on this board, but dear lord is it a piece of shit.

    • 2 weeks ago
      Anonymous

      Just look how clueless rustniles are, this is not even need nowdays, there are intrinsics for this you know.

    • 2 weeks ago
      Anonymous

      In C this is just
      float quake_rsqrt(float x) {
      union { float f; int32_t i; } y = { x };
      y.i = 0x5F375A86 - y.i / 2;
      return y.f * (1.5f - (0.5f * x * y.f * y.f));
      }

    • 2 weeks ago
      Anonymous

      Dumb n-word cretin

  4. 2 weeks ago
    Anonymous

    >defines 1.5F as a constant "threehalfs" for clarity
    >pulls 0x5f3759df out of his ass
    Still tickles me

    • 2 weeks ago
      Anonymous

      0x5f3759df out of his ass
      >Still tickles me
      he didn't pull it out of his ass. it was well known within the computer graphics industry for years before carmack ever saw it - but carmack didn't understand the mathematics behind it. he got credit for introducing it to pc gaming but they tried to claim that ID software had invented it, and gaming magazines republished their nonsense as fact.

  5. 2 weeks ago
    bruce3434

    Fuck you, that's where.

    • 2 weeks ago
      bruce3434

      You're not me.

      • 2 weeks ago
        bruce3434

        Fuck off impersonator.

  6. 2 weeks ago
    Anonymous

    poop

  7. 2 weeks ago
    Anonymous

    I've been trying to either implement this or get one that works but for fixed point
    So far I've gotten
    >https://www.fpgarelated.com/showarticle/1347.php
    But its like 5 iterations so I'd have to do a cycle count to see if its worth it compared to an iterative method.

  8. 2 weeks ago
    Anonymous

    Reminder that carmack the lying hack had literally NOTHING to do with this code. People calling him a genius for it are retarded.

    >the original algorithm was devised by Greg Walsh at Ardent Computer in consultation with Cleve Moler, the creator of MATLAB

  9. 2 weeks ago
    Anonymous

    Whats your favorite trick gee?
    Mine is probably how you can add/sub/mul in parallel 1 16bit and 1 15bit number by leaving bit 16 as the carry for the lower 15bit number.

  10. 2 weeks ago
    Anonymous

    Why do we have this thread every other day?

  11. 2 weeks ago
    Anonymous

    Doesn't it strike anyone else as retarded to half a varible named threehalfs = 1.5F.
    If you change the number, then the variable name is confusing.

  12. 2 weeks ago
    bruce3434

    I am a huge tranny homosexual. Fuck my ass, please negro master.

  13. 2 weeks ago
    bruce3434

    based bruce

  14. 2 weeks ago
    Anonymous

    > "The algorithm was originally attributed to John Carmack, but an investigation showed that the code had deeper roots in both the hardware and software side of computer graphics. Adjustments and alterations passed through both Silicon Graphics and 3dfx Interactive, with the original constant being derived in a collaboration between Cleve Moler and Gregory Walsh, while Gregory was working for Ardent Computing in the late 1980s.[3] Walsh and Moler adapted their version from an unpublished paper by William Kahan and K.C. Ng circulated in May of 1986. "

    confirmed and witnessed: cormack is a fucking hack.

    >What did he mean by this?
    he had no idea how it worked. he stole it. code and math lamers can't explain things they steal.

  15. 2 weeks ago
    Anonymous

    [log in to view media]

    A 20min video explaining the what and why.

    • 2 weeks ago
      Anonymous

      >20 min
      do zoomers are this retarded?

      • 2 weeks ago
        Anonymous

        What is your objection?

    • 2 weeks ago
      Anonymous

      This begs the question: Why doesn't the C std library have a fast sqrt? Development of Quake started way after 1990 why didn't ANSI include the fast sqrt in 1990 and other faster versions of algorithms in ANSI?

      • 2 weeks ago
        Anonymous

        Not all hardware has native floating points, at which point the whole thing becomes more expensive than doing a few iterations of some other method.
        Also, you cant use the same constant with 64 bit numbers or at least nobody has bothered to implement it since there's a sqrt function in modern x86 processors.

        • 2 weeks ago
          Anonymous

          Yeah, but in 1990 x86 was around as a major force at least for 10 years. Most PCs had native floating points. And you might as well as sqrt is super important, just have a fastsqrtfp function.

  16. 2 weeks ago
    Anonymous

    >he
    Stop assuming the people gender.

  17. 2 weeks ago
    bruce3434

    I LOOOOOOVE BBC

    • 2 weeks ago
      Anonymous

      Based American

      • 2 weeks ago
        bruce3434

        Actually, I am a Pakistani homosexual who can't read or write, I just take dick and estrogen pills.

        • 2 weeks ago
          Anonymous

          Based seething American

  18. 2 weeks ago
    Anonymous

    [log in to view media]

    >what the fuck?

  19. 2 weeks ago
    Anonymous

    the most confusing part is the magic constant wtf is that doign

  20. 2 weeks ago
    Anonymous

    john carmack is still based in quake

  21. 2 weeks ago
    Anonymous

    nuke india 2020

  22. 2 weeks ago
    Anonymous

    I understand nothing
    should I learn to program

    • 2 weeks ago
      Anonymous

      Just give up.

  23. 2 weeks ago
    Anonymous

    [log in to view media]

    Everyone knows about fast inverse sqrt, but hardly anyone knows about Minsky's integer circle algorithm.

    x += y >> 4;
    y -= x >> 4;

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