What is the inverse function of f(x) = c/x^(1/n)?

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Discussion Overview

The discussion revolves around the inverse function of the mathematical expression f(x) = c/x^(1/n). Participants are examining the correctness of the proposed inverse function and the conditions under which the functions are considered inverses. The scope includes mathematical reasoning and technical explanation.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant shares a paper and invites comments, indicating a focus on the inverse function and related mathematical concepts.
  • Another participant critiques the choice of variable 'i' in the context of complex numbers and suggests alternatives, highlighting potential clarity issues in the paper.
  • Concerns are raised about the functions f and f^{-1} not being true inverses, with one participant stating this could be a fatal flaw in the paper.
  • Some participants assert that the inverse formula appears correct, providing calculations to support their view.
  • There is a request for clarification on why the functions are not considered inverses, leading to further exploration of the necessary conditions for inverse functions.
  • Participants engage in a back-and-forth discussion about the calculations and the definitions of the functions involved, with one participant offering to show their calculations step-by-step to address the concerns raised.

Areas of Agreement / Disagreement

Participants express differing views on whether the functions f and f^{-1} are indeed inverses. While some believe the calculations support the claim of being inverses, others challenge this assertion, indicating that the discussion remains unresolved.

Contextual Notes

There are unresolved mathematical steps in the calculations presented, and the discussion highlights dependencies on definitions and assumptions regarding the functions and their domains.

roupam
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Hi,

I have written a paper (attached)
I would be happy to get comments on it

Thanks
Roupam

PS.
(Since, there is no independent research in the math section, I have posted here)
 

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On p. 2, in your equation for zeta, i is an unfortunate choice for an index variable since you're working with complex numbers. I suggest k.

On p. 3, "for some constant B and Li(x)" is unclear; it looks like you're making Li(x) constant. Reword if possible. Also "Cramérs conjecture" should be "Cramér's conjecture". (There are a number of minor grammar errors here and throughout, especially overuse of the comma; I'll omit those.)

On p. 6, your functions f and f^{-1} are not inverses. This may be fatal.
 
CRGreathouse said:
On p. 2, in your equation for zeta, i is an unfortunate choice for an index variable since you're working with complex numbers. I suggest k.

On p. 3, "for some constant B and Li(x)" is unclear; it looks like you're making Li(x) constant. Reword if possible. Also "Cramérs conjecture" should be "Cramér's conjecture". (There are a number of minor grammar errors here and throughout, especially overuse of the comma; I'll omit those.)

Being a Comp. Sc. Student, I have the habit of using "i" :smile:
Thanks, I will replace it with something like "a", or "r" etc.

On p. 6, your functions f and f^{-1} are not inverses. This may be fatal.

Can you please tell me why they are not inverses ?
Isnt the inverse formula correct?
 
roupam said:
Being a Comp. Sc. Student, I have the habit of using "i" :smile:
Thanks, I will replace it with something like "a", or "r" etc.

Fine habit, 90% of the time...

roupam said:
Can you please tell me why they are not inverses ?
Isnt the inverse formula correct?

You basically want
f(f^{-1}(x)) = x = f^{-1}(f(x))
for all x, and neither is the case.
 
CRGreathouse said:
You basically want
f(f^{-1}(x)) = x = f^{-1}(f(x))
for all x, and neither is the case.

Well, it seems right to me...

f^{-1}(x) = c^n/x^n
f(x) = c/x^(1/n)

which gives,
f(f^{-1}(x)) = x = f^{-1}(f(x))

And, I am not using the complex roots of x^(1/n), which I stated in the Preliminaries section of the paper that we are only working with positive reals...

Thanks
Roupam
 
roupam said:
Well, it seems right to me...

f^{-1}(x) = c^n/x^n
f(x) = c/x^(1/n)

which gives,
f(f^{-1}(x)) = x = f^{-1}(f(x))

No. If you show your calculations step-by-step we can show you where you're making a mistake.
 
CRGreathouse said:
No. If you show your calculations step-by-step we can show you where you're making a mistake.

Ok, here goes...

f^{-1}(x) = c^n/x^n
f(x) = c/x^(1/n)

which gives,
f(f^{-1}(x)) = c/(f^{-1}(x))^(1/n) = c/(c^n/x^n)^(1/n) = c/(c/x) = x
Again,
f^{-1}(f(x)) = f^{-1}(c/x^(1/n)) = c^n/(c/x^(1/n))^n = c^n/(c^n/x) = x
 

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