💡𝚂𝗆𝖺𝗋𝗍𝗆𝖺𝗇 𝙰𝗉𝗉𝗌📱 @ SmartmanApps @programming.dev

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2 yr. ago

Sorry. I forgot about we were ending daylight savings this past weekend, so the times are actually GMT+10 now.

The syntax is arbitrary in some edge cases

Such as?

I’m taking about physical, non-graphic scientific calculators from the 1990s.

Yep, exact same as the calculator in the linked thread. The expression entered was 6÷2(1+2).

Order of magnitude?

It's actually short for "to the order of", as in 2 squared is 2 to the order of 2. i.e. same thing as Exponent or Index.

order?

It's actually short for "to the order of", as in 2 squared is 2 to the order of 2. i.e. same thing as Exponent or Index.

AFAIK, this is correct to the point that I have understanding of. I’m not a mathematician

I'm a Maths teacher/tutor. The actual rules are Terms and The Distributive Law. There is no such thing as "implicit multiplication" (which is usually people lumping the 2 separate rules together as one and ending up with wrong answers).

My calculator says -2² = -4

That's correct

It is also frustrating when different calculators have different orders of operations and dont tell you.

Yeah, but to be fair most of them do tell you the order of operations they use, they just bury it in a million lines of text about it. If they could all just check with some Maths teachers/textbooks first then it wouldn't be necessary. Instead we're left trying to work out which ones are right and which ones aren't. Any calculator that gives you an option to switch on/off "implicit multiplication", then just run as fast as you can the other way! :-)

Unfortunately some calculators, such as Google's will ignore your brackets and put in their own anyway. You just gotta find a decent calculator in the first place.

Either ‐(n²) or (-n)². Order of operations shouldn’t be some sort of gotcha to trick people into misinterpreting you

It isn't. With ‐(n²), n² is already a single term, so the brackets aren't needed.

I think it was something like : -2 is a diminutive for -1x2

Correct. Things that are usually left out of Maths expressions are plus signs, ones as multipliers/indices, and un-needed brackets. e.g. I could more fully write this as -1(4)², but that just simplifies to -4²

it’s just a squaring a number

The number being squared is 4, unless you put (-4)², otherwise it's 4² with a minus sign.

I think I learned powers take priority over the “-”

Yes, Exponents is the 2nd-highest precedence (after Brackets) - BEDMAS.

A typical scientific calculator didn’t have juxtaposition, so you’d have to enter 6÷2(1+2) as 6÷2×(1+2)

That's not true

you’d get 9 as the answer because ÷ and × have equal precedence and just go left to right

Well, more precisely you broke up the single term 2(1+2) into 2 terms - 2 and (1+2) - when you inserted the multiplication symbol, which sends the (1+2) from being in the denominator to being in the numerator. Terms are separated by operators and joined by grouping symbols.

https://plus.maths.org/content/pemdas-paradox

There's no pemdas paradox, just people who have forgotten the order of operations rules

Even two casios won’t give you the same answer:

The one on the right is an old model. As far as I'm aware Casio no longer make any models that still give the wrong answer.

I’ve never seen a calculator that had bracket keys but didn’t implement the conventional order of operations.

I've seen plenty

This is why every calculator should be a RPN calculator

No, this is why programmers should (re)learn the order of operations rules before writing a calculator.

I just used the calc on window… it cannot respect order of operation

Yeah, I've tried several times to get Microsoft to fix their calculators. I've given up trying now - eventually you have to stop banging your head against the wall.

Math should be just as deterministic as programming, but it’s not in some situations

Maths is 100% deterministic for order of operations. The issue is people not following all of the rules. Order of operations thread index