Solving a partial differential equation using laplace transforms

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This was a great solution, but you were fortunate that the final expression was easy to inverse Laplace transform at the end. A different initial condition would have made this much more challenging.

michaelihill
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I'd appreciate some more videos on differential equations, you don't see many math channels touching them beyond a surface level.

mcalkis
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Great to see Laplace transform used to solve a PDE.
This said, if use the method of separation of variables with an added constant: u(x, t)=f(x)g(t)+c, we can very quickly arrive at the same solution. Things works out nicely because of the initial conditions.
So I wonder if given the initial conditions are defined in such a way the laplace method gives a simple solution is equivalent to using the separation of variable method ?

riadsouissi
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The PDE I think is fun (and insightful) to some via Laplace transforms is u_xx = (1/c^2) u_tt + δ(x - v t), u(0, t) = 0, u(x, 0) = 0, u_t(x, 0), x >= 0. Take LT wrt t ( think). Then the cases v <c (subsonic), v = c (transsonic) and v> c supersonic are different. I hope I remembered everything right. And yes δ is the dirac delta function

Calcprof
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You could also skip using the variation of parameters method if you introduced the Fourier transform of u/U, and do it totally algebraically. That would have brought you to about 10:54 much faster.
I agree, however, that variation of parameters method is an important one to know.

nadavslotky
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Interesting that the boundary conditions create a situation where the homogenous solution doesn’t matter anymore and we only look the particular solution when need to invert it back.

SuperSilver
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❗️❗️🗣️🗣️WE GETTING OUT OF THE ODES WITH THIS ONE🗣️🗣️❗️❗️

danielrosado
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How would you do it with ft tho? I know how for R(1, 1) but not for R(1, 3), since my integrals always seem to diverge...

Qrudi
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Can you plz explain how do you find the value of v1 and v2 in particular solution.

AttiaNaz-pwdo
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Heaviside did this operationally, getting (as you did) e^Sqrt[s] and e^-Sqrt(s), but then interpreted s = d/dt, so we need to compute e^(d^1/2/dt^1/2), the exponential of the 1/2 derivative. See Electromagnetic Theory By O. Heaviside.

Calcprof
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Can you do a playlist about the methods to solve the various types of PDE?

giuliogiacomelli