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Markov2
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Solve $u_y+f(u)u_x=0,$ $x\in\mathbb R,$ $y>0,$ $u(x,0)=\phi(x).$
What's the easy way to solve this? Fourier Transform? Laplace Transform?
What's the easy way to solve this? Fourier Transform? Laplace Transform?
Danny said:I would say separation of variables.
You mean like some level of smoothness. For sure. In most cases I would use a separation of variables. For special cases of $f(u)$ - something else.Ackbach said:Wouldn't you have to say something about $f$ in order for that to work?
What I meant to say was the method of characteristics (What was I thinking?) That's what happens when I think mathematics w/o my first cup of tea in the morning. (Doh)Danny said:I would say separation of variables.
Danny said:You mean like some level of smoothness. For sure. In most cases I would use a separation of variables. For special cases of $f(u)$ - something else.
Thanks for pointing that out!
Danny said:What I meant to say was the method of characteristics (What was I thinking?) That's what happens when I think mathematics w/o my first cup of tea in the morning. (Doh)
Sorry for the delay of the reply, but those books are online? Can you give the links if so?Jester said:What book(s) do you have? You could do a google search for examples or I could give you a list of books that have examples.
A 1st order PDE (partial differential equation) is a mathematical equation that involves partial derivatives of a function of more than one independent variable. In this case, the independent variables are u and x, and the partial derivatives are with respect to u and x.
Solving a PDE means finding a function that satisfies the given equation. In other words, the function u(x,y) must make the equation true for all values of x and y. This can be done by finding a general solution or a particular solution.
The order of a PDE refers to the highest order of the partial derivatives in the equation. In a 1st order PDE, the highest order of the partial derivatives is 1.
The function f(u) is known as the coefficient function and it determines the behavior of the solution u(x,y). In this particular PDE, the coefficient function is multiplied by the partial derivative with respect to x, meaning it affects the slope of the solution in the x-direction.
1st order PDEs are used in various fields of science and engineering, such as fluid mechanics, electromagnetism, and finance. For example, in fluid mechanics, 1st order PDEs can be used to model the flow of fluids in pipes or channels. In electromagnetism, 1st order PDEs can be used to study the propagation of electromagnetic waves. In finance, 1st order PDEs can be used to model the prices of financial assets.