A Beautiful Looking Gaussian Integral - Please HELP

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Discussion Overview

The discussion revolves around a specific Gaussian integral that participants are attempting to solve numerically using MATLAB. The integral involves complex expressions and parameters, and participants are seeking advice on resolving issues encountered during the numerical computation.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Homework-related

Main Points Raised

  • One participant presents a Gaussian integral and expresses difficulty in solving it numerically due to an inconsistency warning in MATLAB.
  • Another participant requests clarification on the article referenced, specifically asking about the notation and the values of constants used in the integral.
  • A participant shares that the article does not provide a solution method but only quotes results, indicating a lack of detailed methodology.
  • Further details about the constants involved in the integral are provided, including specific numerical values and relationships, particularly for the parameter zeta.
  • There is curiosity expressed about how the numerical solution will be approached, especially given the need to vary parameters for different results.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on the solution method for the integral, and multiple viewpoints regarding the interpretation of parameters and notation are present. The discussion remains unresolved regarding the numerical solution.

Contextual Notes

Participants note that certain parameters are treated as constants, but there is ambiguity regarding their values and relationships, which may affect the numerical integration process.

Who May Find This Useful

This discussion may be useful for individuals interested in numerical methods for solving complex integrals, particularly in the context of Gaussian integrals in physics or engineering applications.

n0_3sc
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I have the following Gaussian Integral:

\int_{0}^{\infty}2\pi r\left |{\int_{-l/2}^{l/2}\frac{e^\frac{-r^2}{bH}}{(1+ix)(k^{''} - ik^{'}x)H}}dx\right |^2dr

Where

H = \frac{1+x^2}{k^{''} - ik^{'}x} - i\frac{x - \zeta}{k^{'}}

Assume any characters not defined are constants.

I agree it does look fantastic, and I'm currently trying to numerically solve it (duh..). I'm using MATLAB and I run into the problem:
"Warning: System is inconsistent. Solution does not exist."
Yet I know a solution exists because I'm looking at an article that solved it numerically.

Any Hints/Advice?
 
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n0_3sc said:
I have the following Gaussian Integral:

\int_{0}^{\infty}2\pi r\left |{\int_{-l/2}^{l/2}\frac{e^\frac{-r^2}{bH}}{(1+ix)(k^{''} - ik^{'}x)H}}dx\right |^2dr

Where

H = \frac{1+x^2}{k^{''} - ik^{'}x} - i\frac{x - \zeta}{k^{'}}

Assume any characters not defined are constants.

I agree it does look fantastic, and I'm currently trying to numerically solve it (duh..). I'm using MATLAB and I run into the problem:
"Warning: System is inconsistent. Solution does not exist."
Yet I know a solution exists because I'm looking at an article that solved it numerically.

Any Hints/Advice?

whats the article? it doesn't say how they solved it? what notation are you taking for granted as known? for example is the zeta the riemann zeta fn ( i know not likely since it doesn't have arguments ) but yea if you tell em for what values of the constants you're trying to numerically integrate i'll put it into mathematica and tell you what i get.
 
Hey ice109,
I've attached the article. You'll see the equation on page 1 and 2.
No it doesn't say how they solved it, they just quote the results.
For the notation:
zeta, k'', k' and everything else are just real numbers (constants). Well, for my current purpose they are.

I'm trying to (in a way) reproduce the results in this paper with my own parameters.
Ok, I havn't got all the parameters with me now, but tomorrow I'll grab them and post it here.
 

Attachments

Here are my numbers:

l = 7e-3
b = 14.516e-6
k'' = 11.466e6
k' = 4.387e6
zeta is actually given by:
2*(z-f)/b
where z is a vector that varies from 0 to 10e-3, f is 2.51e-3. But you can try solving it for one particular value of z.

I am curious as too how you will solve this since I need to vary several parameters and obtain different results.
 

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