The title is pretty much the question. My friend (who wants to go to graduate school in Physics) is between two courses the math department offers: an upper-level linear algebra course, and a second course in ODEs. Here are the course descriptions:

and

The school in question is Cornell, in case anyone has further suggestions that could be relevant to Cornell in particular?

I don't know what you're friend has already taken in terms of math, but I would agree with Number Nine. Both of those courses are essentially required if your friend wants to go to grad school for physics.

In my university, you can't get your degree without taking several courses in both of those areas.

Hey there! I'm a physics major at Cornell as well. I agree with the above but if he/she can only pick one of the two then I would personally go with the LA class because it is a pre-req for some important classes that come later on in the Cornell curriculum.

I don't understand how he can take Diff Eq without linear algebra. Has he already taken some "lesser" linear algebra? Perhaps stuck into the calc sequence?

It is usually necessary for at least a chapter of the course when you deal with systems, but I know that in my linear algebra class a lot of the students didn't have linear algebra- they just had to spend more time learning the linear algebra. The instructor also did a short review of some of the necessary LA. Although, I would recommend a student taking ODE's to at least have knowledge of basic linear algebra...