Solving Cauchy problem for first order PDE

How to solve the following Cauchy problem using MATLAB: x*U_x + y*U_y = U+1; U(x,y)= x^2 on y= x^2
I was trying using the following command: dsolve('Dx=x','Dy=y','Du=u+1');
But the problem is how to apply Cauchy data? Please advice.

2 个评论

What Cauchy data? You have not shown any data.
As well, you might also explain what you intended by the expression:
U+!

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回答(1 个)

Torsten
Torsten 2017-2-13
编辑:Torsten 2017-2-13
There is no ready-to-use MATLAB program to solve this kind of problem.
I suggest you look up "method-of-characteristics". Your PDE can be solved analytically.
Best wishes
Torsten.

3 个评论

Sir, the command which I wrote is computing characteristics only but the problem is that how to include the Cauchy data in the command? Please suggest. Thank you
Don't know if it works, but you'll see how to proceed:
syms x(s) y(s) u(s) X0
[solx,soly,solu] = dsolve(diff(x,s)==x, diff(y,s)==y, diff(u,s)==u+1, x(0)==X0, y(0)==X0^2, u(0)==X0^2);
[X0sol,ssol]=solve([solx==x,soly==y],[X0,s]];
subs(solu,[X0,s],[X0sol,ssol])
Best wishes
Torsten.
programming is not correct

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