Re: Not to incite a language war but apparently the Corona lockdown was based on 13 year old undocumented C-Code

[Optikos <ZUERCHER_Andreas@outlook.com>]

On Sunday, May 17, 2020 at 2:20:56 PM UTC-5, Niklas Holsti wrote:
> On 2020-05-17 20:38, Optikos wrote:
> 
>     ...
> 
> > Despite your best efforts to side track the issue, we are trying to
> > discuss topics that would be applicable to Anatoly's new Ada model,
> > so that his doesn't have the same defects as Ferguson's.
> 
>     ...
> 
> > We don't need to discuss never-ending wispy cloud formations of
> > what-if Ada code in our imaginations anymore.  We have Anatoly's
> > extant source code to review and suggest improvements upon.
> Fine, I'm not preventing you from doing that. But Anatoly's program is 
> based on very different modelling principles and computational methods, 
> so any comparison to Ferguson's code will hardly illuminate the C-vs-Ada 
> aspects any more than comparing any chosen C code to any chosen Ada 
> code, solving different problems.
> 
> >> 3. Whether the epidemiological models and assumptions of Ferguson's
> >> group are correct
> > 
> > You keep basing so many of your pronouncements on a one-size-fits-all
> > monolithic definition of correctness (and that Ferguson is definitely
> > in possession of that One True And Only CorrectnessⓇ).
> That is a false claim. I have never claimed to know anything about the 
> correctness of Ferguson's models.

On this and the bulk of all of your replies on this posting, methinks you doth protest too much.  Obviously, you are intentionally trying to stifle free and open debate on this topic.  Only you can divulge why you do that.

As to your demonstrably false claim that you never made any claims at all about the correctness or validity of Ferguson's model or its design beyond its implementation in C/C++ source code, let's review your prior postings above:

On Wednesday, May 13, 2020 at 9:05:50 AM UTC-5, Niklas Holsti wrote:
> On 2020-05-13 16:52, Optikos wrote:
> > On which date did they fix the problem?  Before or after governments
> > acted on the miscalculations?
> 
> There has been no demonstration that the early predictions from this 
> program, that prodded governments into action, were "miscalculations" to 
> any significant degree, especially after the recommended practice of 
> performing several runs and considering the ensemble of results.

That is a judgement not only of the correctness of the source code itself, but also that the model produces results that are not miscalculations/over-estimates that are trustworthy enough to be actionable by governments that were prodded into action by those trustworthy results.

On Tuesday, May 12, 2020 at 5:20:14 PM UTC-5, Niklas Holsti wrote:
> On 2020-05-13 0:27, Jeffrey R. Carter wrote:
> > This is different from the kind of non-determinism of simulations
> > that are intended to be run many times with different RNG seeds.
> 
> Yes indeed, and I would not call that non-determinism of the code. The 
> reviewer also condemned that kind of stochastic exploration and seemed 
> to confuse it with real non-determinism. It is true that Monte Carlo is 
> often used when the system being simulated is chaotic in some way so 
> that its behaviour is essentially unpredictable, and can be so sensitive 
> that no practical floating-point precision can give a truly reliable end 
> result in any given simulation.

That is another judgement-of-validity on Ferguson's choice of stochastic model's algorithm itself*, not its implementation in source code.  The reviewer is discussing primarily the design and by cascading ramification the implementation too by using the code as a proxy for a missing design document, but your defense quoted above discusses not so much the source code, but the stochastic algorithm itself as Ferguson's valid modeling design decision.

* that would apply to implementing that design in any other language

On Monday, May 11, 2020 at 3:27:06 PM UTC-5, Niklas Holsti wrote:
> On 2020-05-11 21:49, Rick Newbie wrote:
> > I want to share this article here before it gets buried in the memory hole
> > https://chrisvoncsefalvay.com/2020/05/09/imperial-covid-model/
> 
> …
> 
> - The authors of the code defended the non-determinism by saying that 
> the simulation is statistical, anyway, and that all simulations should 
> be repeated several times to get an ensemble of possible behaviour. The 
> reviewer did not accept this defense, but insisted on determinism. 
> However, I know of at least one example where non-determinism is 
> accepted and used in this way: simulations of many-body gravitational 
> systems, such as planetary systems, where it is very common to compute 
> thousands or millions of simulations and then estimate the likelihood of 
> particular final outcomes (say, the ejection of one planet from the 
> system) from the ensemble of simulations.

That is yet another judgement-of-validity on the non-determinism in Ferguson's choice of algorithmic design* of the model, not the source code itself.

* that would apply to implementing that design in any other language