I would strongly advise you to take Math 20F (Linear Algebra) before Math 20D (Differential Equations), despite how that seems alphabetically out of order. Why? Because a few classes into 20D last quarter, my Prof basically said that the current order is weird (she has taught both courses) because 20D uses matrices a lot, yet there isn’t enough time to go over them in detail in 20D, so you basically have to hope learning matrices in a rushed fashion mostly from the book will work for you (it didn’t work well enough for me and definitely affected my grade). And now that I am taking 20F, I can further corroborate this since so far (and looking a bit ahead in the textbook), 20F seems like it could be summarized as “Matrices 101″.

So, save yourself a lot of pain and:

Take 20F before 20D!

If you have any questions, feel free to use the Comments section.

Summary

Let me give you a rundown of what happened:

1. When my enrollment time came around, all the seats for 15L were full, so I put myself on the waitlist.
2. Some time later, UCSD’s CSE Department sent out a notice that a new section of the class had opened up. Unfortunately, this new section conflicted badly with my schedule, so I did not remove myself from the waitlist. For reasons that I’ll come to in a second, here’s a redacted copy of the email:

This e-mail is intended for students waitlisted in:
CSE 15L (list of sections redacted)

To all students waitlisted in CSE 15L [list of sections redacted]:
A new section has opened for CSE 15L!

You have been cleared to enroll in CSE 15L [section identification redacted],
[identification information about the new section redacted]

If this lab time works for you then you are free to enroll on Webreg.

If you have any questions or concerns please contact:
[contact information redacted]

3. After the passage of some time, I checked and saw I was now 1st on the waitlist. I thought to myself, “Yay! It won’t be long now!”
4. A day or so later, at 11PM, I get an email from TritonLink saying that it tried to add me to the class but I didn’t satisfy the prerequisites and thus was dropped from the waitlist.
   • (A) WTF!? Why did you even let me put myself on the waitlist then? Or why didn’t I get a warning message about this?
   • (B) Liar! I do very much indeed satisfy the prerequisites! Again, WTF!?
5. I go to CSE Advising to complain. The receptionist says the department is aware of the problem and has me put my name down on a clipboard of affected people.
6. A day or 2 passes. The deadline for adding classes is drawing near.
7. I go to CSE Advising again, this time to see my actual advisor. After a long wait (I don’t blame that on the department; I could have gotten a reservation), I am told by my advisor that everyone on the waitlist had been given priority for the new section, which was barring me from adding any other section of 15L. Nowhere was this mentioned in the email above, and the phrasing does nothing to suggest it. She removes the priority and I successfully enroll using a computer in the lobby.

Conclusion

Overall, this pisses me off because:

• TritonLink should have been smarter. Its error email should have mentioned this hidden “priority” and its implications. Not to mention that its prereq-checking definitely leaves something to be desired.
• The department’s email should have mentioned and explained this priority and its implications. As it was phrased, it did not suggest taking any action if the lab time did not work for you; that’s obviously wrong as action was very much necessary. [EDIT: I want to emphasize that I don't hold the writer particularly at fault and don't think they should be reprimanded, but rather I think the Department would do well to learn from this example in the future.]

Update [added 1/31/09]

I have since sent feedback to TritonLink and got a quick and kind, albeit vague and not entirely satisfying, email response about how their development team is taking all feedback into account (while not mentioning any specifics about my problems), and that my comments were also forwarded to the Registrar’s office since they relate to the Waitlist process, which I appreciate.

I also sent a formal letter by post to the CSE Department regarding their role in this and how they could improve the situation. I have yet to receive a response.