- #1
Verdict
- 117
- 0
Homework Statement
First of all, for a different problem, I have the following written down:
[tex]\frac{\frac{{\partial{}}^2\varphi{}}{\partial{}u^2}}{{\left(\frac{\partial{}\varphi{}}{\partial{}u}\right)}^2}[/tex]
Where phi is a function of u, which is a function of x and y. Also, u is harmonic.
Now, I want to rewrite this in some suggestive form, if there is one.
Now, onto my other question:
Homework Equations
Uhm, I can't really think of any at this point. Maybe the rotation matrix to rotate the strip?
The Attempt at a Solution
Concerning the rewriting: I already thought of
[tex]\frac{\partial{}}{\partial{}u}\left(\frac{-1}{\frac{\partial{}\varphi{}}{\partial{}u}}\right)[/tex] but I somehow want it to be a function of phi, and I don't think this qualifies as such.
Alright, and then the dirichlet problem. In my course, we haven't done any complicated PDE's yet whatsoever, so I checked with the teacher and he doesn't want a general formula, just a specific solution that works.
For question a, I found a solution:
(a+b)/2 - (a-b)/2 * X
seems to satisfy the conditions given.
Now for B, I somehow need to rotate and translate and scale the strip to the same one as the first. However, I don't understand how. If I understand correctly, I need to 'move' the plane bounded by y = x and y = x + 2 to the plane bounded by x = -1 and x = 1.
In order to use the rotation matrix, I have to make y = x and y = x + 2 into a vector first though. I don't really understand how, so it would be great if someone could give me a hint!