Toronto Math Forum
APM3462012 => APM346 Math => Misc Math => Topic started by: Shu Wang on October 14, 2012, 01:25:44 AM

sorry for stealing the post; I've got a question regarding to Example 3 and 4 on Lecture 7.
How do you turn the Robin boundary conditions to a function of psi and phi?

sorry for stealing the post; I've got a question regarding to Example 3 and 4 on Lecture 7.
How do you turn the Robin boundary conditions to a function of psi and phi?
It is not stealing but hijacking. Just plug $u=\phi(x+ct)+\psi (xct)$ into b.c. and you get a mixture of $\psi'(ct)$, $\psi(ct)$ and $\phi'(x+ct)$, $\phi(ct)$. But you know $\phi(ct)$ so you get 1st order ODE for $\psi$.

rofl, thanks alot.