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Glitch in the matrix (ani.social)

submitted 11 months ago by Toes@ani.social to c/196@lemmy.blahaj.zone

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[-] SmartmanApps@programming.dev 1 points 8 months ago

Please see this section of Wikipedia on the order of operations

That section is about multiplication, and there isn't any multiplication in this expression.

The “math” itself might not be ambiguous, but how we write it down absolutely can be

Not in this case it isn't. It has been written in a way which obeys all the rules of Maths.

This is why you don’t see actual mathematicians arguing over which one of these calculators is correct

But I do! I see University lecturers - who have forgotten their high school Maths rules (which is where this topic is taught) - arguing about it.

it is not either calculator being wrong

Yes, it is. The app written by the programmer is ignoring The Distributive Law (most likely because the programmer has forgotten it and not bothered to check his Maths is correct first).

US - PEMDAS vs UK - BODMAS

Those aren't the rules. They are mnemonics to help you remember the rules

notice division and multiplication swapped places

Yes, that's right, because they have equal precedence and it literally doesn't matter which way around you do them.

you can’t actually do all of the multiplication and division at one time

Yes, you can!

Some are taught to simply work left to right

Yes, that's because that's the easy way to obey the actual rule of Left associativity.

we are all taught to use parentheses correctly to eliminate ambiguity

Correct! So 2(2+2) unambiguously has to be done before the division.

[-] Crozekiel@lemmy.zip 1 points 8 months ago

Just out of curiosity, what is the first 2 doing in "2(2+2)"...? What are you doing with it? Possibly multiplying it with something else?

there isn’t any multiplication in this expression.

Interesting.

I really hope you aren't actually a math teacher, because I feel bad for your students being taught so poorly by someone that barely has a middle school understanding of math. And for the record, I doubt anyone is going to accept links to your blog as proof that you are correct.

[-] SmartmanApps@programming.dev 1 points 8 months ago

Just out of curiosity, what is the first 2 doing in “2(2+2)”…? What are you doing with it? Possibly multiplying it with something else?

Distributing it, as per The Distributive Law. Even Khan Academy makes sure to not call it "multiplication", because that refers literally to multiplication signs., which, as I said, there aren't any in this expression - only brackets and division (and addition within the brackets).

I feel bad for your students

My students are doing well thanks.

I doubt anyone is going to accept links to your blog as proof that you are correct

You mean the blog that has Maths text book references, historical Maths documents, and proofs? You know proofs are always true, right? But thanks for the ad hominem anyway, instead of any actual proof or evidence to support your own claims.