Recursive function in a physics equation

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Discussion Overview

The discussion centers around the concept of recursive functions in physics equations, exploring their validity, representation, and potential applications. Participants share their thoughts on how recursion might manifest in physical equations and seek clarification on specific examples.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant seeks examples of recursive functions in physics equations and expresses uncertainty about their validity.
  • Another participant questions the definition of recursion, providing two forms: one involving a sequence and another involving a self-referential equation.
  • A participant presents an equation, v(t) = 3 * v(t), and discusses the challenge of specifying a terminating condition, questioning how to express a value greater than 8 * PI.
  • One participant argues that the only physical solution to the presented equation is zero, citing a contradiction in assuming a positive solution.
  • Another participant invites further explanation of the recursive concept and expresses interest in the topic, indicating they have encountered similar ideas.
  • A participant mentions fractals in relation to recursion, suggesting that many fractals are generated by recursive algorithms.
  • A later reply confirms that many fractals are indeed recursive, affirming the connection between recursion and fractals.

Areas of Agreement / Disagreement

Participants express varying levels of understanding and perspectives on recursion in physics. There is no consensus on the validity of the specific equation presented or how to approach it, and multiple viewpoints on recursion and its applications remain evident.

Contextual Notes

Participants have not fully resolved the mathematical implications of the recursive equation discussed, and assumptions about the nature of recursion in physics are not explicitly defined.

noize11
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Hoping someone can point out an example of a recursive function in a physics equation. If this is not a valid step that would be great to hear about too. Also if anyone has even tried to introduce such an equation in the past or how it might be represented. [I'm not the best student of maths].

I have a form in mind that I can only express with recursion.


Thanks in advance.
 
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What do you mean by recursion? Is it of the form:
[itex] x_{n+1} = f(x_n)[/itex]
or is it something like
[itex] y = f(y)[/itex]
where f(y) is some nasty integral or something which you can't solve?

In either case, yes, recursion occurs a lot in physics and is the basis for things like perturbation theory.

Matt
 
Something more along these lines:

[tex]v(t) = 3 * v(t)[/tex]

Obviously this equation cannot be solved as there is no terminating condition specified. Trying to solve this when t=1 for instance gives:

[tex]v(1) = 3* (3* (3 * (3 * (3* ...))))[/tex]

I have a structure that relies on this form of recursion, but how do I go about specifying the terminating value? For instance, suppose I simply wanted a value > 8 * PI. How is it that I would express this?
 
Hmm, either something fishy is going on or you need help from a mathematician (which sadly I'm not).

By my reconing the only 'physical' solution to your equation is zero. My argument would run as follows:

Assume [itex]v(t)[/itex] has a solution [itex]v(t)>0[/itex].

[itex]v(t) = 3 v(t) \Rightarrow 1 = 3[/itex]
This is a contradiction hence [itex]v(t)=0[/itex].

Unless I am wrong in thinking your symbol [itex]*[/itex] means multiply?

Ok, as I said before I am not a mathematician so if I've done something stupid please don't hurt me :)

Matt
 
Would you like to explain better what you are trying to do. It is interesting your topic and please give us details. I really don't know what to say about your recursive physics, but I ran into similar ideas, too. Maybe I can help :)
 
fractals

BreAkeR said:
Would you like to explain better what you are trying to do. It is interesting your topic and please give us details. I really don't know what to say about your recursive physics, but I ran into similar ideas, too. Maybe I can help :)

Aren't fractals recursive?
 
mee said:
Aren't fractals recursive?

If by that you mean a great many of them are generated by recursive algorithms, then yes they definitely are.

Matt
 

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