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Comment by User23 | Hacker News Reader

This is one of the best examples I’ve ever seen supporting the claim that analogies aren’t reasoning.

Edit: apparently elaboration is in order. In mechanical engineering one deals with smooth functions. A small error results in a small propensity for failure. Software meanwhile is discrete, so a small error can result in a disproportionately large failure. Indeed getting a thousandth of a percent of a program wrong could cause total failure. No bridge ever collapsed because the engineer got a thousandth of a percent of the building material’s properties wrong. In software the margin of error is literally undefined behavior.

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>No bridge ever collapsed because the engineer got a thousandth of a percent of the building material’s properties wrong.

Perhaps not with building properties, but very small errors can cause catastrophic failure.

One of the most famous ones would be the Hyatt Regency collapse, where a contractor accidentally doubled the load on a walkway because he used two shorter beans attached to the top and bottom of a slab, rather than a longer beam that passed through it.

https://en.m.wikipedia.org/wiki/Hyatt_Regency_walkway_collap...

In electrical engineering, it's very common to have ICs that function as a microcontroller at 5.5V, and an egg cooker at 5.6V.

Microsoft lost hundreds of millions of dollars repairing the original Xbox 360 because the solder on the GPU cracked under thermal stress.

It's definitely not to the same extreme as software, but tiny errors do have catastrophic consequences in physical systems too.

From the GP comment:

> Engineers design bridges with built-in safety margins in order to guard against unforeseen circumstances (unexpectedly high winds, corrosion causing joints to weaken, a traffic accident severing support cables, et cetera)

I am not a mechanical engineer, but none of these examples look like smooth functions to me. I would expect that an unexpectedly high wind can cause your structure to move in way that is not covered by your model at all, at which point it could just show a sudden non-linear response to the event.

They are smooth in that they are continuously differentiable.

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