Solutions of the wave equation's little brother

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The discussion revolves around a partial differential equation (PDE) given by ∂f/∂z = -1/v ∂f/∂t, questioning whether a function f(z,t) must take the form g(z-vt). It is noted that while functions of the type g(z-vt) are solutions, the general solution for PDEs differs significantly from that of ordinary differential equations (ODEs). A proposed approach is to explore a general solution of the form f(z,-vt) = g(z)h(-vt) to investigate potential solutions. The linear nature of the equation allows for solutions to be expressed as sums of such functions, which ultimately remain within the same functional form. The conclusion emphasizes that any linear combination of these functions still adheres to the original solution type.
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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:

\frac{\partial f}{\partial z}=-\frac{1}{v}\frac{\partial f}{\partial t}

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

f(z,-vt)\,=\,g(z)h(-vt) 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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