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There's no function application in circuitry. See > It looks like it feeds its output to the input and then repeats. But it doesn't, it just maintains the same

• dahart 4y ago
  > There’s no function application in circuitry. Why do you say that? Of course there is. It would be more accurate to say all circuitry is built out of function applications, both analog and digital. If you can write an equation for the voltage on a given trace, the circuit applies a function. If you can write a truth table for a given component, that’s a function applicator. The whole reason we can build software functions is because we build them on top of circuit functions. Saying feedback doesn’t exist because it’s just electrons is like saying people are just atoms; it ignores the structure of the system. While all electric circuits pump electrons, signal feedback is a physical reality, one that you can even see & hear first-hand in some circuits. The OP maybe forgot momentarily to think about capacitors and time-varying inputs when they claimed analog circuits don’t have a time component.
  • mxkopy 4y ago
    For context I'm talking about function application a la lambda calculus. In this case 'function application' is something that's done to discrete symbols. Circuits aren't a discrete system however so there's no mapping. Functions are a good way to describe things but it's not what they are fundamentally. OP also made a good point about how the inputs can change with the outputs but it's not recursive. It's literally the same process as water flowing more slowly into a lake as the lake gets more full. My intuition with circuits is that you'll end up doing something like that if you try to feed the output to the input without an intermediary store like a delay line or capacitor. And even then it's not recursive unless the algorithm you're running is tail optimized.
    • dahart 4y ago
      > Circuits aren’t a discrete system however so there’s no mapping. You need to qualify that as analog circuits. And they do accept a discrete mapping, you’re just asserting without trying it. > Functions are a good way to describe things but it’s not what they are fundamentally. Yes it is. It is both how and why we build circuits; to apply the function’s effect, to pass it to the next function to build a larger function. Why are you suddenly ruling out capacitors and delay lines? Those are analog circuitry, and they are absolutely standard building blocks. > it’s not recursive unless the algorithm you’re running is tail optimized. What’s wrong with tail optimized? That is still recursive, and it’s still feedback. You’re moving the goal posts. Above you and OP stated feedback (tail-recursion) was not a thing in analog circuits. That’s not true.
      • mxkopy 4y ago
        > You’re moving the goal posts. To my credit the goalposts were never defined. > You need to qualify that as analog circuits. No, I don't. The context always has been analog circuits. OP makes the distinction here > Analog electronics is different from digital computation because it's not about inputs and outputs, cause and effect in the same manner. Good faith needs to be established before I continue, sorry
        • dahart 4y ago
          Oh sorry I was referring to the goal posts you defined with “There’s no function application in circuitry”, and repeating the OP’s claim that what looks like feedback actually isn’t feedback because circuits are in a static electric balance (which is not generally true for analog circuits). Okay, I accept that the context was analog circuits, that’s fair, and I apologize for accidentally ticking you off with that note. I didn’t mean to, and I felt like a broad generalization could use the qualification, and all it needs is a single word. But I don’t see how that side-comment amounts to bad faith about anything, nor do I agree with that assessment. I’m arguing directly and with evidence against the claims you made, not with hyperbole, not with ad-hominem, but with facts: analog circuits with feedback are not just something that exists, they are widespread and common. Power conditioners, frequency filters, analog guitar delay pedals, all of these things are real-world counter-examples to the way OP framed it, and the way you defended that claim.