Generating polynomials for a multistep method

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Discussion Overview

The discussion revolves around the concept of generating polynomials in the context of multistep methods for solving ordinary differential equations (ODEs), specifically focusing on their implementation in difference equations.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant expresses confusion regarding the implementation and understanding of generating polynomials in the context of the difference equation for a general ODE.
  • Another participant suggests that working through numerous examples may help clarify the concept.
  • A participant indicates a lack of clarity about how generating polynomials relate to specific methods, such as the three theta methods and the implicit Euler method.
  • There is a mention of notes that refer to generating polynomials without providing sufficient motivation or explanation of their purpose.
  • A participant references an external source, a Wikipedia page on generating functions, as a potential resource for further understanding.

Areas of Agreement / Disagreement

Participants generally express confusion and seek clarification on the concept of generating polynomials, indicating that multiple views on understanding the topic remain unresolved.

Contextual Notes

Participants note a lack of detailed explanation in their materials regarding what generating polynomials generate and how the methods are motivated, which may limit their understanding.

Who May Find This Useful

Individuals interested in the mathematical foundations of multistep methods for ODEs, particularly those seeking clarification on generating polynomials and their applications.

dynamicskillingme
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Hi, I'm struggling to understand how the generating polynomials work and are implemented in the difference equation for a general ODE y' = f(t,y)
Difference Equation
D%20h%20%5Csum_%7Bj%3D0%7D%5E%7Bk%7D%20b_%7Bj%7D%20f%28t_%7Bn+j%7D%2C%20y_%7Bn+j%7D%29.gif

Generating polynomials
%7D%20%5C%5C%20%5Csigma%20%28w%29%20%3D%20%5Csum%5E%7Bk%7D_%7Bj%3D0%7D%20b_%7Bj%7D%20w%5E%7Bj%7D.gif

"Coefficients are normalized either by a_k = 1 or sigma(1) = 1
 
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You can gain understanding by doing examples: lots and lots of examples.
Do you have a specific question?
 
Sorry if I wasn't clear enough, I don't understand the concept behind the generating polynomials. My notes state the examples of the three theta methods but I can't understand how they are obtained (e.g. implicit euler is sigma(w) = w )
 
You notes just say there are these things called generating polynomials that can be used t help solve ODE's but does not tell you what they generate or how the method is motivated?

Have you seen:
https://en.wikipedia.org/wiki/Generating_function
 

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