• laserm@lemmy.worldEnglish
    24·
    2 天前

    Why would a mathematician use j for imaginary numbers and why would engineer be mad at them?

    • CyanideShotInjection@lemmy.worldEnglish
      24·
      2 天前

      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.

    • dustycups@aussie.zoneEnglish
      9·
      2 天前

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

    • ThePuy@feddit.nlEnglish
      8·
      2 天前

      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.

    • LeFrog@discuss.tchncs.deEnglish
      521·
      3 天前

      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.

    • TheSlad@sh.itjust.worksEnglish
      18·
      3 天前

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

      • Chakravanti@monero.townEnglish
        2·
        2 天前

        That’s hilarious. You’re not seeing what’s going on backwards just like that (as I point at the point going nowhere shitty) in an equation that is finding as many clAEver ways to say something you actually not caring about talking about.

        That’s like, "How many time van express the only thing that van’t be done until the 'verse itself tries to do what can’t be done and sever your…

        …Oh, I see…you don’t have ([of course, because you can’t have to give {is}) nothing)] to give.

        Unable to sea time doesn’t mean we can’t see(k)ER the mAETh.ac(k).cc(k).08

        The only thin(g):(k) that doesn’t ever be never, is not at alla hack(g)in(g).G your lackthereof to divi…

    • Kogasa@programming.devEnglish
      20·
      3 天前

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

      • Zagorath@aussie.zoneEnglish
        3·
        3 天前

        “operative” instead of, uh, something else

        I think they meant “operand”. As in, in the way dy/dx can sometimes be treated as a fraction and dx treated as a value.

          • Zagorath@aussie.zoneEnglish
            2·
            2 天前

            The operand is the target of an operator

            Correct. Thus, dx is an operand. It’s a thing by which you multiply the rest of the equation (or, in the case of dy/dx, by which you divide the dy).

              • Zagorath@aussie.zoneEnglish
                1·
                2 天前

                You’re misunderstanding the post. Yes, the reality of maths is that the integral is an operator. But the post talks about how “dx can be treated as an [operand]”. And this is true, in many (but not all) circumstances.

                ∫(dy/dx)dx = ∫dy = y

                Or the chain rule:

                (dz/dy)(dy/dx) = dz/dx

                In both of these cases, dx or dy behave like operands, since we can “cancel” them through division. This isn’t rigorous maths, but it’s a frequently-useful shorthand.

                • Chrobin@discuss.tchncs.deEnglish
                  1·
                  2 天前

                  I do understand it differently, but I don’t think I misunderstood. I think what they meant is the physicist notation I’m (as a physicist) all too familiar with:

                  ∫ f(x) dx = ∫ dx f(x)

                  In this case, because f(x) is the operand and ∫ dx the operator, it’s still uniquely defined.

  • iAvicenna@lemmy.worldEnglish
    55·
    3 天前

    operative?

    Also mathematicians use i for imaginary, engineers use j. The story does not add up. I have never seen a single mathematician use j for imaginary.

    • sartalon@lemmy.worldEnglish
      7·
      3 天前

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

      • iAvicenna@lemmy.worldEnglish
        6·
        2 天前

        Interesting I never saw j from a maths person. Friends (from a decade ago!) in electronics eng dep said they use j because i was reserved for current. perhaps the latter depends on the department.

        • Chakravanti@monero.townEnglish
          1·
          2 天前

          j is pretention when a math doer does it. j is for engineers and you don’t even understand the bubble ratio filtering equation let alone be asking to envision what temp you did the mAEth in.

          You got lost in the number of letters instead of realizing the MeTowel’s important presence til that EOTU moment of that manufa turing of Big Black Goles you get to watch it all happen again as Thanos facepalms.

    • GandalfTheDumb@lemmy.worldEnglish
      64·
      3 天前

      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.

      • ryedaft@sh.itjust.worksEnglish
        3·
        3 天前

        OPs boyfriend is obviously an i engineer and hates j engineers. No one can stay angry at mathematicians - engineers on the other hand…

              • Jarix@lemmy.worldEnglish
                5·
                3 天前

                I clicked your link, I barely made it out of highschool so I have no idea what any of it means, but I like reading things I shouldn’t understand anyway, sometines it’s so interesting even without understanding.

                So I thank you!

                • Klear@sh.itjust.worksEnglish
                  3·
                  2 天前

                  Quaternions are the closest we get to lovecraftian horror in real life.

                  Four dimensional and mostly imaginary, they were carved into a stone bridge by a crazy mathematician in a fit of madness, Lord Kelvin called them “unmixed evil”, and the Mad Hatter from Alice may have been inspired by them.

                  Also they have been a curiosity at best for a long time, despite the efforts of a secret Quaternion Society, but they suddenly blew up in usefulness in modern times as they happen to be an easy and fast way for computers to describe rotations in 3D space, so they’re everywhere.

                  Yeah, lovecraftian as shit.

        • CodexArcanum@lemmy.dbzer0.comEnglish
          14·
          3 天前

          It gets worse actually. You can define a number system using any power of 2 amount of i-like units in a similar relationship to quaternions using the Cayley-Dickson construction

          Fascinatingly, you lose some property of the algebra at each step. Quaternions aren’t commutative: ABC != CBA. Octonians aren’t associative: (AB)C != A(BC). Once you get into 16 i’s with subscripts, it really gets crazy.

          (Also, I just got the joke. Damnit @HappyFrog@lemmy.blahaj.zone your serious answer threw me off!)

    • grysbok@lemmy.sdf.orgEnglish
      11·
      3 天前

      [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.

    • bitcrafter@programming.devEnglish
      6·
      3 天前

      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.

    • burntbacon@discuss.tchncs.deEnglish
      11·
      2 天前

      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.

  • jsomae@lemmy.mlEnglish
    2·
    2 天前

    My initial thought was that it’s surprising that the engineer is using i whereas the mathematician is using j. But I know some engineers who are hardcore in favour of i. No mathematicians who prefer j though. So if such an engineer were dating a mathematician of all people who used j, I could see that being ♠ .

  • vivalapivo@lemmy.todayEnglish
    29·
    3 天前

    As a physicist I can’t understand why would anyone complain about a +jb or $\int dx f(x)$. Probably because we don’t fuck