Mastodawn

Wouter Lindenhof 3d ago

@matthiasott

It’s a symbol and not a unit. So it’s “50% of 1 meter is 50 cm”.

Source: https://styleguide.iec.ch/?docs=iec%2Ftypographic%2Funits-and-symbols

Matthias Ott

@DevWouter “The internationally recognized symbol % (per cent) may be used with the SI. When it is used,
a space separates the number and the symbol %.”
Source: https://www.bipm.org/en/publications/si-brochure
🤓
I think using it without the space is more common in English, though, you are right. This is an interesting source, by the Chicago Manual of Style: https://www.chicagomanualofstyle.org/qanda/data/faq/topics/Abbreviations/faq0097.html

SI Brochure - BIPM

SI Brochure

BIPM

Wouter Lindenhof 3d ago

@matthiasott

Going a bit further the 9th version of the SI also to put a space between it.

Looking at the back of nutrition values of (Dutch) peanut butter I noticed that in the second column it mixes both styles.

And most formatting strings don’t add space between percentages.

Fluff! This is annoying. 😁😣

Matthias Ott 3d ago

@DevWouter 🤪😂

💡𝚂𝗆𝖺𝗋𝗍𝗆𝖺𝗇 𝙰𝗉𝗉𝗌📱3d ago

@matthiasott @DevWouter
I don't know who wrote those style guides, but we def write both units and percentages without spaces. I think it might be a knock-on effect from a weird thing that has been happenning in recent years where people start putting spaces between everything in Maths - 2 + 2 = 4, instead of 2+2=4 - and I have no idea how that became a thing to begin with. I have to tell my students to stop doing it because online answers have no spaces and will mark as wrong if there's spaces

@SmartmanApps @matthiasott

That might have a different cause? Such as "E = mc2" describes 3 values where the right side describes a multiplication?

Did a bit more digging, but couldn't find the reason, but I assume the space rule was used to take poor penmanship/printing into account so that one could avoid that "50% of 9g and 1l" be confused with 500/0 of 99 and ll". This also explains the few exceptions (such as degrees and angles)

💡𝚂𝗆𝖺𝗋𝗍𝗆𝖺𝗇 𝙰𝗉𝗉𝗌📱2d ago

@DevWouter @matthiasott
"describes 3 values where the right side describes a multiplication?" - no, the right side is a single Term/Product, whereas mxc² would be multiplication of 2 Terms https://dotnet.social/@SmartmanApps/110846452267056791

"the few exceptions (such as degrees and angles)" - there are no exceptions in Maths - no spaces between scalar and units

💡𝚂𝗆𝖺𝗋𝗍𝗆𝖺𝗇 𝙰𝗉𝗉𝗌📱 (@[email protected])

Attached: 1 image #MathsMonday week 2, Terms. Simply put, in #Mathematics Terms are separated by operators and joined by brackets. The most common example is 2a=(2*a). This makes it simpler to write fractions. e.g. 1/2a rather than 1/(2*a). That also means 1/2a isn't mistaken as half a, which would actually be written as a/2. Notice in the latter that the a is to the left of the division, which means it's in the numerator, and vice-versa for the former (more about this aspect of #Maths #Math later, but first)...

dotnet.social

Yes on the first part: multiplication should have been product. (Quick question: Would it be correct to say that the product, although a single term, by it self contains two terms?)

As for the second part, I was talking about the official standards such as SI, NIST, etc.

💡𝚂𝗆𝖺𝗋𝗍𝗆𝖺𝗇 𝙰𝗉𝗉𝗌📱2d ago

@DevWouter
"although a single term, by it self contains two terms?" - no, 2 factors, and the first factor is usually referred to as the coefficient (and is usually the numerical part if it has one, such as 2ab, though theoretically any factor can be the coefficient)

Thanks for explaining. Did some more reading up on the subject and I think I understand it now.

Quick check to verify: The equation E=mc^2 has:
- 2 Terms: E, mc^2
- 3 Factors: E, m, c (of which `c` is a constant)

💡𝚂𝗆𝖺𝗋𝗍𝗆𝖺𝗇 𝙰𝗉𝗉𝗌📱2d ago

@DevWouter
Yes, that's right. mc² has to be a single term so that you can substitute it in anywhere that you have an e - 1/mxc² would give wrong answers (c²/m), 1/mc² doesn't. BTW the exponent 2 is available in Unicode - on Windows the code is 253 (bizarrely squared is 253 and cubed is 252 - the other way around would be easier to remember!)

Wouter Lindenhof 1d ago

Right, that makes sense. I now recall that is was explained to me as having a higher precedence than if it were written as a multiplication. Never truly understood that until now.

The reason for ^2 is because I don’t have that key on iPhone.

💡𝚂𝗆𝖺𝗋𝗍𝗆𝖺𝗇 𝙰𝗉𝗉𝗌📱1d ago

@DevWouter
"higher precedence than if it were written as a multiplication" - that's because ab=(axb) by definition, thus has the precedence of brackets. In the acronyms, M refers LITERALLY to multiplication SIGNS. i.e. axb, rather than ab. If a=2, b=3, then axb=ab, 2x3=6, axb=2x3, ab=6

Wouter Lindenhof 1d ago

I only mentioned it as proof that my math education was sorely inadequate and that I’m only now connecting some of the dots. 😁

💡𝚂𝗆𝖺𝗋𝗍𝗆𝖺𝗇 𝙰𝗉𝗉𝗌📱1d ago

@DevWouter
Yeah, depends on how good a teacher you had. I had a useless teacher in Year 10. Fortunately not the case in other years. Some of them introduce products (poorly) by saying "we can write axb as ab", and some people bury this deep in their memory and make a false equivalence that conversely ab can be written as axb. It can't, or 1/ab will give wrong answers since 1/axb is a different answer, b/a. ab only ever equals (axb).

💡𝚂𝗆𝖺𝗋𝗍𝗆𝖺𝗇 𝙰𝗉𝗉𝗌📱1d ago

@DevWouter
Funnily enough, just today I had someone falsely claiming 1/2x is ambiguous 🙄 No it isn't!

Fish Face 2d ago

@DevWouter have you seen a reference for where mc² is explicitly declared to not be a multiplication? Clearly it's equal to m×c² for any value of m (c being constant only has one value), so I think it can happily be called multiplication. A typical explanation might be "multiplication of a and b can be written as ab, a•b, or a×b. They all mean the same thing".

@FishFace

It’s more that my terminology was wrong. The product here is the result of a multiplication. The product describes the term, the multiplication the operation.

Keep in mind that the discussion was about definitions of math and how it should be typed.

Fish Face 1d ago

@DevWouter yes you can make such a distinction but it can lead to issues if you assume that others always make it very carefully. I would say that the word product *emphasises* the result while multiplication *emphasises* the operation. At least, with this in mind, you won't be led astray when others do just that!

These style guides are, at the end of the day, a bit esoteric and arbitrary. But stuff looks nicer if everything is coherent, unlike in the picture!

Wouter Lindenhof 1d ago

@FishFace

I think we all are in agreement that being a bit pedantic is a requirement in this discussion. 😁