The only thing I can think of is that the OP studied electrical engineering at some point. But it’s a 4chan story so probably fake anyway.

I think it might be the wrong way around: Engineers like to use j for imaginary numbers because i is needed for current.

Mathematicians are taught to be elastic with notation, because they tend to be taught many different interpretations of the same theory.

On the other hand engineers use more strict and consistent notation, their classes have a more practical approach.

Using the same notation makes it faster to read and apply math, a more agile approach helps with learning new theories and approaches and with being creative.

The associativity thing also doesnt make sense.

imaJinary

TIL engineers can’t spell for shit.

Engineer here: mostly use i, but have seen j used plenty. First time I saw j used was by a maths professor.

As an EE, I used both. Def not a mathematician though. Fuck that, I just plug variables into programs now.

Cannot confirm, we always used i.

Integrals are an expression that basically has an opening symbol, and an operation that is written at the end of it that is used also as a closing symbol, looks kinda like:$ {some function of x} dx.

The person basically said “the dx part can be written at the start also, and that would make my so mad :3”: $ dx {some function of x}.

This gets their so mad because understandably this makes the notation non-standard and harder to read, also you’d have to use parentheses if the expression doesn’t just end at the function.

Note: dollar used instead of integral symbol

An integral is usually written like ∫ f(x) dx or alternatively as df(x)/dx. Please note that this is just a way to apply the operation ‘Integration’, like + applies the operation ‘Addition’. There is no real multiplication or division.

But sometimes you can take a shortcut and treat dx as a multiplied constant. This is technically not correct, but under the right circumstances lands you at the same solution as the proper way. This then looks like this ∫ f(y) dy/dx dx = ∫ f(y) dy

Another thing you can do is to move multiplicative constants from inside the Integral to in front of the Integral: ∫ 2f(x) dx = 2 ∫ f(x) dx. (That is always correct btw)

What anon did was combine those two things and basically write ∫ f(x) dx = dx ∫ f(x). Which is nonsensical, but given the above rules not easily disproven.

This is more or less the same tactic used by internet trolls just in a mathy way. Purposefully misinterpreting arguments and information, that cost the other party considerably more energy to discover and rebut. Hence the hate fuck.

Right? They got that shit backwards. Op is a fraud. i is used in pure math, j is used in engineering.

As an engineer I fully agree. Engineers¹ aren’t even able to do basic arithmetics. I even cannot count to 10.

¹ Except maybe Electrical engineers. They seem to be quite smart.

The mathematician also used “operative” instead of, uh, something else, and “associative” instead of “commutative”

How do we know it’s gay though? OP could be a girl (male)

My thoughts exactly lol

Yes but everyone knows physicists like weird notations

But the post says before the integral, so I understand what they did would be $dx \int f(x)$, which is disgusting

Web dev here. “Huh?”

Medical here. “Huh?”

Something something distance calls for norm, not just squares.

||i||² + ||1||² = 2

Imagining your death. :P

But seriously, it’s perfectly sensible when remember that i is just the mathematical representation of “left turn”, just like -1 is the mathematical representation of “go backwards”-- and as we know, two left turns sends you backwards. So think about this triangle in the following way:

Imagine you are a snail, starting at the origin. Now imagine that you walk forward 1 step along the horizontal line. Then you turn 90° to the left to start walking along the vertical line, but then, because you need to walk i steps along this line you take another 90° turn to the left, which means that you are now walking backwards and you end up back at the origin. How far away from the origin are you? Zero steps.

no, d…do you have a plan?

This one made me laugh almost as much as the OP. Thank you!

Thado-mathocist. The real chad all along.

It makes me wonder if somewhere out there in a multiverse, a community of lisping incels all collectively draw the chad wojak as as an aramaic looking dude.

Well done, truly

That part also got me really confused. All the mathematicans I know use i while engineers use i or j depending on the kind of engineer. I’ve never seen a Pikachu engineer using anything other than j.

The fun starts when you study quaternions

i^2 = j^2 = k^2 = ijk = −1

I agree. Clearly i is current. What is this i=√-1 nonsense.

[Lapsed] mechanical engineering gang checking in. I was also surprised. Though, tbh, I think it came down to personal preference of the professor more than field-wide consensus.

a real mathematician would use (0, 1) instead of i

I just think of the definition of a derivative.

d is just an infinitesimally small delta. So dy/dx is literally just lim (∆ -> 0) ∆y/∆x. which is the same as lim (x_1 -> x_0) [f(x_0) - f(x_1)] / [x_0 - x_1].

Note: ∆ -> 0 isn’t standard notation. But writing ∆x -> 0 requires another step of thinking: y = f(x) therefore ∆y = ∆f(x) = f(x + ∆x) - f(x) so you only need ∆x approaching zero. But I prefer thinking d = lim (∆ -> 0) ∆.

If not fraction, why fraction shaped?

Hate ****

I too take hate shits on the toilet.

Anger bang

As a software dude I can see you wrote a regex, I just can’t find out what you’re trying to match.

😏