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NYarvin's profile
Norman Yarvin
Norman Yarvin
Norman Yarvin
@NYarvin

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Norman Yarvin

@NYarvin

yarchive.net/blog
Joined April 2013

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    1. Matt Ridley‏Verified account @mattwridley May 10
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      Matt Ridley Retweeted David Davis

      "In the respective words of four experienced modellers, the code is “deeply riddled” with bugs, “a fairly arbitrary Heath Robinson machine”, has “huge blocks of code – bad practice” and is “quite possibly the worst production code I have ever seen”."https://twitter.com/DavidDavisMP/status/1259421989648904197 …

      Matt Ridley added,

      David DavisVerified account @DavidDavisMP
      In today's Sunday @Telegraph @mattwridley and I outline the weaknesses of Professor Ferguson's model. https://www.telegraph.co.uk/news/2020/05/10/chilling-truth-decision-impose-lockdown-based-crude-mathematical/amp/ …
      82 replies 168 retweets 412 likes
    2. Jon Rimmer‏ @jonrimmer May 10
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      Replying to @mattwridley @afneil

      In the words of @ID_AA_Carmack (famously skilled programmer; made Doom and Quake), who assisted Microsoft in cleaning up the code for release: "Bugs were found and fixed, but generally in paths that weren't enabled or hit".

      3 replies 0 retweets 0 likes
    3. Jon Rimmer‏ @jonrimmer May 10
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      Replying to @jonrimmer @mattwridley and

      "That was my fear — what if the code turned out to be a horror show, making all the simulations questionable? I can’t vouch for the actual algorithms, but the software engineering seems fine."

      1 reply 0 retweets 0 likes
    4. Rogerborg‏ @RogertheBorg1 May 10
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      Replying to @jonrimmer @mattwridley and

      That speaks to the hobbyist standards of Carmack then. Have you looked yourself? Non-deterministic (same seed, same inputs = random outputs), zero unit, integration or regression tests. You can't tell what it's meant to do, or prove that it does it.https://github.com/mrc-ide/covid-sim/tree/master/src …

      1 reply 0 retweets 0 likes
    5. John Carmack‏Verified account @ID_AA_Carmack May 10
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      Replying to @RogertheBorg1 @jonrimmer and

      Go build the code and run it single threaded with the same seed. You get the same results. There was a regression check doing that during the brief time I worked on it. Nobody is going to defend this code as a paragon of style, but it is functional.

      4 replies 1 retweet 3 likes
      Norman Yarvin‏ @NYarvin May 10
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      Replying to @ID_AA_Carmack @RogertheBorg1 and

      Getting seriously different results for different seeds isn't even a sign of anything being wrong. In the real world, too, epidemic spread depends a lot on random events. It only took one person to infect the Diamond Princess; that easily might not have happened.

      12:05 PM - 10 May 2020
      1 reply 0 retweets 0 likes
        1. New conversation
        2. Rogerborg‏ @RogertheBorg1 May 10
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          Replying to @NYarvin @ID_AA_Carmack and

          Are you actually sane? Accidental randomness is a bug, not a feature. Why have a pseudo random seed if the result is non-deterministic anyway? I thank God every day that I work with people with higher standards than that.

          1 reply 0 retweets 1 like
        3. Norman Yarvin‏ @NYarvin May 10
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          Replying to @RogertheBorg1 @ID_AA_Carmack and

          The proper way to do this is to do a lot of runs and report the average and standard deviation. (Which they tell you to do, but really the code should do it itself.) But with the transmissibility data being garbage, the output has to be garbage anyway.

          1 reply 0 retweets 0 likes
        4. 3 more replies

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