How Can the Logit Function Be Modified for a Specific Output Range?

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Discussion Overview

The discussion revolves around modifying the logit function, specifically the logistic function, to achieve a specific output range. Participants explore how to adapt the function so that it meets certain conditions based on the input variable z, particularly focusing on the behavior of the function around the value of 0.5.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant proposes shifting the logit function by replacing z with z - 0.5 to achieve the desired output conditions.
  • Another participant questions the terminology used, suggesting that the function in question is actually the logistic function rather than a "logit" function.
  • Some participants express confusion about the terminology and the nature of the function being discussed, indicating a lack of clarity on the definitions involved.
  • A participant raises a technical question regarding the use of the range [-∞, +∞] and whether actual infinity is being considered as an input.

Areas of Agreement / Disagreement

There is no consensus on the terminology used (logit vs. logistic function), and participants express differing views on the nature of the function being discussed. The discussion remains unresolved regarding the correct interpretation and modification of the function.

Contextual Notes

Participants have not fully clarified the definitions of the terms used, and there are unresolved questions about the implications of using infinity as an input in the function.

adan
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Hi,
I am looking for changing the logit f(z) = 1/(1+exp(-z)), where z range is [-inf,+inf]. I want to adapt it as follows:
if z > 0.5 then f > 0.5
z < 0.5 then f < 0.5

Thanks
 
Last edited:
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Hi,
If I understand you well, you want to shift the graph to the right by 0.5. So replace ##z## by ##z-0.5##

1624359059346.png
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BvU said:
Hi,
If I understand you well, you want to shift the graph to the right by 0.5. So replace ##z## by ##z-0.5##

View attachment 284871##\ ##
Thank you so much!
 
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adan said:
I am looking for changing the logit f(z) = 1/(1+exp(-z))
Do you mean logistic function? That is apparently how @BvU interpreted this. I don't believe there is such a thing as a "logit" function.
 
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Me too... :rolleyes:

Never too old to learn 😎

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Actually, the ##f## in this thread is the sigmoid function. Vaguely remember it's used in neural networks and fuzzy control.

##\ ##
 
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adan said:
Hi,
I am looking for changing the logit f(z) = 1/(1+exp(-z)), where z range is [-inf,+inf]. I want to adapt it as follows:
if z > 0.5 then f > 0.5
z < 0.5 then f < 0.5

Thanks
Just a technicality : Why are you using #[\-infty, \infty]#, i.e., are you considering #\pm \infty # as actual inputs?
 
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