wischi

@wischi@programming.dev

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wischi,

The joke is because of “degrees” (also to measure angles) and “radians”

wischi, (edited )

Joules is unfortunately a vector because it’s over a distance in a direction.

What? Joule is an energy unit and energy is a scalar quantity and not a vector. There is no “energy direction” and no “distance”.

Edit: even your edit doesn’t make sense. Provide a source that says that energy or joule is somehow a vector.

wischi,

The calculator section is actually pretty important, because it shows how there is no consensus. Sharp is especially interesting with respect to your comment because all scientific Sharp calculators say it’s 1. For all the other brands for hardware calculators there are roughly 50:50 with saying 1 and 9.

So I’m not sure if you are suggesting that thousands of experts and hundreds of engineers at Casio, Texas Instruments, HP and Sharp got it wrong and you got it right?

There really is no agreed upon standard even amongst experts.

wischi,

❤️ True, but I think one of the biggest problems is that it’s pretty long and because you can’t really sense how good/bad/convining the text is it’s always a gamble for everybody if it’s worth reading something for 30min just to find out that the content is garbage.

I hope I did a decent job in explaining the issue(s) but I’m definitely not mad if someone decides that they are not going to read the post and still comment about it.

wischi,

What is the correct answer according to the convention you follow?

wischi, (edited )

👍 That was actually one of the reasons why I wrote this blog post. I wanted to compile a list of points that show as clear as humanity possible that there is no consensus here, even amongst experts.

That probably won’t convince everybody but if that won’t probably nothing will.

wischi, (edited )

Thank you so much for taking the time. I’m also not convinced that APS’s notation is a very good choice but I’m neither american nor a physisist 🤣

I’d love to see how the exceptions work that the APS added, like allowing explicit multiplications on line-breaks, if they still would do the multiplication first, but I couldn’t find a single instance where somebody following the APS notation had line-break inside an expression.

wischi, (edited )

In this case it’s actually the absence of sources. I couldn’t find a single credible source that states that ÷ has somehow a different operator priority than / or that :

The only things there are a lot of are social media comments claiming that without any source.

My guess is that this comes from a misunderstanding that the obelus sign is forbidden in a lot of standards. But that’s because it can be confused with other symbols and operations and not because the order of operations is somehow unclear.

wischi,

Thank you very much 🫶. No it’s not annoying at all. I’m very grateful not only for the fact that you read the post but also that you took the time to point out issues.

I just fixed it, should be live in a few minutes.

wischi,

🤣 I wasn’t even sure if I should post it on lemmy. I mainly wrote it so I can post it under other peoples posts that actually are intended to artificially create drama to hopefully show enough people what the actual problems are with those puzzles.

But I probably am a fool and this is not going anywhere because most people won’t read a 30min article about those math problems :-)

wischi, (edited )

True, and it’s not only about learning math but that there is actually no consensus even amongst experts, about the priority of implicit multiplications (without explicit multiplication sign). In the blog post there are a lot of things that try to show why and how that’s the case.

wischi,

Exactly. With the blog post I try to reach people who already heared that some people say it’s ambiguous but either down understand how, or don’t believe it. I’m not sure if that will work out because people who “already know the only correct answer” probably won’t read a 30min blog post.

wischi,

I’d really like to know if and how your view on that matter would change once you read the full post. I know it’s very long and a lot of people won’t read it because they “already know” the answer but I’m pretty sure it would shift your perception at least a bit if you find the time to read it.

wischi, (edited )

The problem with BODMAS is that everybody is taught to remember “BODMAS” instead of “BO-DM-AS” or “BO(DM)(AS)”. If you can’t remember the order of operations by heart you won’t remember that “DM” and “AS” are the same priority, that’s why I suggested dropping “division” and “subtraction” entirely from the mnemonic.

It’s true that calculators also don’t dictate a standard but they implement what conventions are typically used in practice. If a convention would be so dominating (let’s say 95% vs 5%) all calculator manufacturers would just follow the 95% convention, except maybe for some very special-purpose calculators.

wischi,

I’m not sure if you read the post yet but I also have a short section about alternative notations which are less ambiguous or never ambiguous. RPN has the same issue as most notations that are never ambiguous namely that it’s hard to read - especially for big expressions.

wischi,

That’s actually a great way of putting it 🤣

wischi, (edited )

It’s not really a calculator engineering problem. If you don’t have time to read the entire blog you should definitely check out the section “But my calculator says…”. It’s actually about order of operations regarding implicit multiplication.

wischi,

Yes it’s the other way round. Parentheses are top priority.

wischi, (edited )

In the blog post there are even more. Texas Instruments, HP and Canon also have calculators, and some of them show 9 and some 1.

wischi,

In a scientific context it’s actually very rare to run into that issue because divisions are mostly written as fractions which will completely mitigate the issue.

The strong implicit multiplication will only cause ambiguity after a division with inline notation. Once you use fractions the ambiguity vanishes.

In practice you also rarely see implicit multiplications between numbers but mostly between variables or variables and their coefficients.

wischi,

I’m not sure if I’d call it the “scientific” one. I’d actually say that the weak juxtaposition is just the simple one schools use because they don’t want to confuse everyone. Scientist actually use both and make sure to prevent ambiguity. IMHO the main takeaway is that there is no consensus and one has to be careful to not write ambiguous expressions.

wischi,

If you are not kidding, can you show your steps I can try to help you, but I can’t currently think of a way how you’d end up with 15.

wischi, (edited )

That’s just wrong. “Kilo” is ancient Greek for “thousand”. It always meant 1000. Because bytes are grouped on powers of two and because of the pure coincidence that 10^3 (1000) is almost the same size as 2^10 (1024) people colloquially said kilobyte when they meant 1024 bytes, but that was always wrong.

Update: To make it even clearer. Try to think what historical would have happened if instead of binary, most computers would use ternary. Nobody would even think about reusing kilo for 3^6 (=729) or 3^7 (=2187) because they are not even close.

Resuing well established prefixes like kilo was always a stupid idea.

wischi,

Could also be small hands, so he probably would also have to take someone else’s fist to really prove it.

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