Gaussian normal distribution curve

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Discussion Overview

The discussion revolves around the search for a mathematical function that resembles the Gaussian normal distribution curve but is defined over a finite interval, terminating at a specific point rather than extending to infinity. Participants explore various mathematical formulations and properties of such functions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • One participant seeks a function that has a Gaussian shape but is defined to be zero beyond a finite x = X.
  • Another participant suggests defining the Gaussian function for a finite interval, specifying that it equals zero outside that interval.
  • A different formulation is proposed: f(x) = Ae^{-x^2} - b for |x| < \sqrt{\ln(A/b)} and 0 elsewhere, noted for its continuity.
  • Another suggestion is a raised cosine function, specifically 1 + cos(x), defined over the interval -π < x < π.
  • A participant questions the possibility of a non-piecewise function that can be defined for the entire range of x with a single mathematical relationship.
  • One response argues that a non-piecewise function may not exist due to the requirements imposed, suggesting the use of a Heaviside function to create a single expression that meets the criteria.

Areas of Agreement / Disagreement

Participants express differing views on the existence of a non-piecewise function that meets the specified criteria, indicating that multiple competing ideas remain unresolved.

Contextual Notes

Some limitations include the dependence on specific definitions of functions and the conditions under which they are considered valid, as well as the unresolved nature of the mathematical formulations discussed.

touqra
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I am looking for a mathematical equation which is similar to the Gaussian normal distribution curve, but I need one which terminates at a finite x = X and not at infinity, ie, [tex]f(x \geq X) = 0[/tex], but, [tex]f(x \leq X) =[/tex]a function which has a Gaussian shape-like curve.
Is there one such as this that you know or in mathematics literatures?
 
Physics news on Phys.org
define the Gaussian for any finite interval
f(x)
= gaussian for a<x<b
= 0 otherwise

-- AI
 
Or consider:
[tex]f(x)=Ae^{-x^2}-b[/tex]
for [itex]|x|<\sqrt{\ln(A/b)}[/itex] and 0 elswhere.
That one is even continuous.
 
Or even just a raised cosine, 1 + cos(x) : -pi < x < pi .
 
Is there a mathematical function which is not piece-wise and can be defined for the whole range of x (just by one mathematical relationship)?
 
Probably not since you are splitting the range up in your own requirements, besides, that is purely a superficial issue for you. If you know what a heaviside function is then, for k some positive real number

H(x+k)(1-H(x-k))f(x)

for some suitably shaped and nomalized function would do and would appear to be a nice single line wouldn't it? Of course

H(y) is defined piecewise.
 

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