• bitcrafter@programming.dev
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      2 months ago

      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.

  • Avicenna@lemmy.world
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    2 months ago

    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.world
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      2 months ago

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

    • Unlearned9545@lemmy.world
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      2 months ago

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

      • Avicenna@lemmy.world
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        2 months ago

        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.

  • laserm@lemmy.world
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    2 months ago

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

    • CyanideShotInjection@lemmy.world
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      2 months ago

      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.

    • ThePuy@feddit.nl
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      2 months ago

      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.

  • Phoenix3875@lemmy.world
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    2 months ago

    I think rather d/dx is the operator. You apply it to an expression to bind free occurrences of x in that expression. For example, dx²/dx is best understood as d/dx (x²). The notation would be clear if you implement calculus in a program.

  • marcos@lemmy.world
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    2 months ago

    Hum… I don’t think the integral “operator” applies by multiplication.

    You can put the dx at the beginning of the integral, but not before it.

    • OrganicMustard@lemmy.world
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      2 months ago

      If you were using nonstandard analysis with dx an infinitesimal you could put it outside I guess. Maybe with differential forms too?

      • marcos@lemmy.world
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        2 months ago

        Switch it with a summation operator and see if it makes sense. The problem isn’t the operation by itself, but the fact that the operator implies an argument application, like a function.

        • OrganicMustard@lemmy.world
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          2 months ago

          In the case of dx as an infinitesimal it makes sense. You are making a sum of all the values of the function in the integral range and multiplying with a constant dx.

      • Kogasa@programming.dev
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        2 months ago

        In the context of differential forms, an integral expression isn’t complete without an integral symbol and a differential form to be integrated.

  • jsomae@lemmy.ml
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    2 months ago

    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 ♠ .