Classifying ODE's: What Determines Linearity and Order?

  • Context: Graduate 
  • Thread starter Thread starter Lengalicious
  • Start date Start date
  • Tags Tags
    Classification
Click For Summary

Discussion Overview

The discussion revolves around the classification of ordinary differential equations (ODEs), specifically focusing on determining their linearity, order, and homogeneity. Participants explore examples and seek clarification on the definitions and implications of these classifications.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant questions whether classifying an ODE involves identifying it as linear or non-linear and determining its order.
  • Another participant provides an example of an ODE and suggests it is second order, non-linear, and heterogeneous, while also questioning the homogeneity of a different equation.
  • A participant mentions additional classifications for second order ODEs based on solvability and references Maple software for classification assistance.
  • There is a discussion about the homogeneity of specific equations, with one participant asserting that an equation is homogeneous if it does not contain terms that depend solely on the independent variable.
  • Another participant challenges the homogeneity of an equation by pointing out the presence of a specific term, suggesting it is not homogeneous.

Areas of Agreement / Disagreement

Participants express differing views on the classification of specific ODEs, particularly regarding the definitions of homogeneity and the implications of certain terms in the equations. The discussion remains unresolved as participants offer competing interpretations.

Contextual Notes

Limitations include potential misunderstandings of the definitions of linearity, order, and homogeneity, as well as the reliance on specific examples that may not cover all cases. The discussion does not resolve the criteria for classification.

Lengalicious
Messages
162
Reaction score
0
When classifying an ODE do I just say whether its linear / non-linear and what order it is?

EDIT: Example: x2x'' + e-xx = t3 where x is function of t.

is this 2nd order, non linear and heterogeneous?

Also, would dx/dt = logte-x be homogeneous because both terms contain the dependent variable 't'?
 
Last edited:
Physics news on Phys.org
There are some more classifications for (second order) odes, mostly based on the fact that the ode is solvable (or not) when it is of a certain class. I like the choice of the Maple software, which is pretty classic. The online description of odeadvisor giving you a classification is here:
http://www.maplesoft.com/support/help/Maple/view.aspx?path=DEtools/odeadvisor

Your first order ode is homogeneous, because it does not have a term that only depends on t. dx/dt=a(t)*x+b(t) is not homogeneous, but dx/dt = a(t)*x is. Your example is also separable, which means it can be solved using separation of variables.
 
so if dx/dt = logte-1, would that now mean that this was no longer homogeneous? Thanks for the help by the way.
 
Your equation is not homogeneous because of the t cubed term.
 

Similar threads

  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 2 ·
Replies
2
Views
3K
Replies
3
Views
3K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 7 ·
Replies
7
Views
3K