Solition problems with Matlab (12 PDE with 8 variables))

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Discussion Overview

The discussion revolves around the challenges faced by a master’s student in solving a set of 12 partial differential equations (PDEs) with 8 variables using Matlab, specifically in the context of high energy physics and monopole instanton solutions. The focus is on numerical convergence issues and the formulation of the equations derived from a Lagrangian approach.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • The original poster describes their use of Matlab with the Optimization toolbox and the finite difference method to solve the equations but reports a lack of convergence.
  • Some participants express curiosity about the generation of more equations than unknown functions, questioning the formulation of the problem.
  • One participant notes that the system is overdetermined, suggesting that having more equations than variables could lead to a fine numerical solution, yet the original poster's program still fails to converge.
  • The original poster mentions using an ansatz that incorporates gauge and Higgs variables in spherical coordinates, which leads to the generation of the 12 equations of motion.
  • There is a request for clarification regarding what is meant by "variables," indicating potential confusion or differing interpretations of the term within the context of the discussion.

Areas of Agreement / Disagreement

Participants express differing views on the implications of having more equations than variables, with some questioning the formulation while others accept it as a characteristic of the problem. The discussion remains unresolved regarding the convergence issue and the interpretation of variables.

Contextual Notes

The discussion highlights potential limitations in the formulation of the equations, such as assumptions regarding the nature of the variables and the dependence on the specific ansatz used. There are also unresolved mathematical steps related to the convergence of the numerical method employed.

tiantsai
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Hi, I am a master student comes from USM in Malaysia. I don't know my problem should placed on differential forum or high energy physics forum. Anywhere, My current study is high energy physics subject and my main study is focus on monopole instanton solution in static form which did not include time, i using the Lagrangian to generate out the 12 set equations of motion with 8 variables, the software that i use is Matlab with Optimization toolbox- the algorithm that i use inside the package is trusted reflective region and the numerical method that i used is finite difference method. However, it did not converge. I have tried to reproduce the Jutta Kunz paper-monopoles solution with 6 set of partial differential equation with 6 variables and its work well and i also obtain the Higgs field \Phi(r,\theta) of monopole successfully. The variables that in the set of equations of motion is in r and \theta form which means as A(r,\theta). So any suggestion for using Matlab to solve the 12 set equations of motion (PDE form) with 8 variables.
 
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I am very intriqued how you managed to "generate" more equations than unknown functions.
 
My professor say its is a overdetermined system with because the number of partial equations is more than the variables and suppose it can give us a fine numerical solution for each variables but my program still cannot converge...
 
Well i am using the ansatz which include gauge and Higgs variable that in the form of spherical coordinate (also include internal and external space), so putting inside the Lagrangian and its generate out 12 equations of motion with 8 variables.
 
what do you mean by "variables"?
 

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