# Toronto Math Forum

## APM346-2018S => APM346--Lectures => Topic started by: Adam Gao on March 19, 2018, 06:18:38 PM

Title: Unbounded Terms
Post by: Adam Gao on March 19, 2018, 06:18:38 PM
Why do we drop unbounded terms from solutions to PDE's? Specifically, in section 6.2, Laplace equation in half-strip:

$$Y''= \lambda Y$$

yields solution

$$Y=Ae^{-\sqrt{\lambda}y}+Be^{\sqrt{\lambda}y}$$

And then the second term is dropped because it is unbounded

Title: Re: Unbounded Terms
Post by: Victor Ivrii on March 19, 2018, 07:48:49 PM
We are looking for a bounded solution. You may consider this as "boundary condition at infinity"