Solutions of the wave equation's little brother

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Discussion Overview

The discussion revolves around the properties and solutions of a partial differential equation (PDE) related to wave equations. Participants explore the implications of a specific PDE and whether the form of a function satisfying it must conform to known solution types.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant questions whether a function f(z,t) that satisfies the PDE \(\frac{\partial f}{\partial z}=-\frac{1}{v}\frac{\partial f}{\partial t}\) must necessarily be of the form g(z-vt), despite knowing that such functions are solutions.
  • Another participant suggests exploring a general solution of the form f(z,-vt) = g(z)h(-vt) to investigate further.
  • A participant notes the distinction between general solutions to PDEs and ordinary differential equations (ODEs), indicating a lack of experience with the former.
  • It is mentioned that since the equation is linear, solutions could also be any sum of functions of the type g(z-vt).
  • One participant reiterates that sums of functions of that type are also functions of that type, emphasizing the linear nature of the solutions.

Areas of Agreement / Disagreement

Participants express differing views on whether the form of f(z,t) must be restricted to known solution types, indicating that the discussion remains unresolved.

Contextual Notes

Participants acknowledge the complexity of general solutions to PDEs compared to ODEs, highlighting potential limitations in their understanding and approach.

quasar987
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Suppose I showed that a function f(z,t) of which I do not know the form explicitely satisfies the following pde:

[tex]\frac{\partial f}{\partial z}=-\frac{1}{v}\frac{\partial f}{\partial t}[/tex]

While it is certain that functions of the type g(z-vt) are solutions to the pde, does it mean that my f(z,t) is of this form necessarily?
 
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Well, one could try a general solution

[tex]f(z,-vt)\,=\,g(z)h(-vt)[/tex] and see where that takes one.
 
One understand that general solutions to pde are quite different from general solution to ode and one has no experience in dealing with the former.
 
Since that is a linear equation, solutions may also be any sum of functions of that type.
 
HallsofIvy said:
Since that is a linear equation, solutions may also be any sum of functions of that type.
But sums of functions of that type are also functions of that type.
 

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