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My first programming role was on the back of work by an engineer in this article. The core of the solver was a FORTRAN implementation of a paper on p-convergen
by icks 4y ago
My first programming role was on the back of work by an engineer in this article. The core of the solver was a FORTRAN implementation of a paper on p-convergence. It was really amazing seeing our software predict how a small crack in a part of an aircraft would propagate. The 3D model produced matched the photograph shared later.
The lead developer (at the time) once said that the biggest software failure we can have is not incorrect results, but incorrect results without the user knowing. This is probably why I am so bothered by silent failures in my big company role now.
- wheelinsupial 4y agoI know it's not a simple answer, but how would you embed checks to flag or highlight potentially incorrect results to the user?
- kqr 4y agoFor physical processes, you can sometimes lean on conservation laws. Financial, no-arbitrage "laws". Sometimes it can help to run two different models, or different numerical methods, and compare their results. More generally, it's very, very hard. I am fairly sure there are multiple published results in computational fluid dynamics that are subtly wrong.
- meheleventyone 4y agoA lot of computer models are deliberately wrong but useful as well which is another ball game in terms of analysing results.
- badpun 4y ago> I am fairly sure there are multiple published results in computational fluid dynamics that are subtly wrong. I wonder what that means for the accuraccy of the climate models...
- thrown_22 4y agoAll models are wrong, some are useful.
- geysersam 4y agoIt's probably impossible to accurately simulate the climate of the planet decades into the future. That does not meaningfully detract from the evidence for human caused global warming however.
- halffaday 4y agoI have to applaud the subtle elegance of the sarcasm here
- geysersam 4y agoNo sarcasm intended. The science of climate change rests on many legs. It was already established long before massive models on the scale we have today were possible. Computer simulations attempts to understand how it will affect us, but does not contribute much evidence.
- jeffreyrogers 4y agoThey are all wrong. Historically they've overpredicted warming, and then the models are updated to fit the (new) data better. They perform worse in areas with less data, like polar regions. To forestall knee-jerk downvotes: I'm not saying climate change isn't real or that anthropogenic global warming doesn't exist. I'm saying the models are not yet developed enough to predict very accurately. Early heliocentric models made poor predictions too because they assumed circular rather than elliptical orbits, they were still more "right" than geocentric models.
- brutusborn 4y agoCan you suggest good places to look for more info on this? I have tried a few times to find info on the accuracy of these models and couldn't find much. And most models seem to be closed source.
- simplotek 4y ago> I know it's not a simple answer, but how would you embed checks to flag or highlight potentially incorrect results to the user? For starters, some problems do have analytical solutions. Yo can compare a FEM model of these problems with the known analytical solution and see if it's close enough or not. One of them is the elasto-plastic plate with a hole. You can also run unit tests at the element level.