#### Elementary Differential Equations II

“Even after that manipulation we still have some work left. We can’t get away with no work, we are not politicians.”

**Text: **Diffy Qs: Differential Equations for Engineer by J. Lebl

**Prof:** Dr. Ian Frigaard

Dr. Frigaard was a humorous prof who had a lot of practical insights from an engineering perspective. The teaching was largely focused on examples, though a bit of theory was chucked in now and then for good measure. He was willing to humor a theoretical question if he had a bit of time.

**Difficulty**

I took it in the summer, so the material was probably simplified. The material is mainly straight-forward: we mostly practice lengthy manipulations involving Fourier Series. We had a quiz a week after the first week and he said he chucked the lowest quiz. All homework was optional, which was good because the homework was really lengthy (I am guessing the homework is mandatory during winter). While the quizzes generally tested basic questions on each topic, the final had slightly more complex questions.

**Key Concepts**

Fourier Series

Partial Differential Equations

Series Solutions

Separation of Variables

** Hard Concepts**

D’Alembert’s Solution: Requires drawing of graphs, something I am not very efficient at.

Messy Algebra: The algebra on the final was a mess, with horrid fractions in each question, so get some practice.

Sturm-Liouville Theory: Slightly confusing until you realize you are not trying to solve the general Sturm-Liouville problem.

**Conclusion**

Very example heavy class. Mainly learned about 5 equations which had very similar solutions involving Fourier series and separation of variables. Would prefer a class where we learn more techniques and are exposed to a wide variety of equations instead. The algebra is also really gross.