Notes on Diffy Qs: Differential Equations for Engineers - Textbook, edition 6.11, 2026
Jiří Lebl

@article{,
title= {Notes on Diffy Qs: Differential Equations for Engineers - Textbook, edition 6.11, 2026},
journal= {},
author= {Jiří Lebl},
year= {2026},
url= {https://www.jirka.org/diffyqs/},
abstract= {From the author:

*A first course on differential equations, aimed at engineering students. The prerequisite for the course is the basic calculus sequence. This free online book (OER more formally) should be usable as a stand-alone textbook or as a companion to a course using another book.*
 
*The aim is to provide a low cost, redistributable, not overly long, high-quality textbook that students will keep rather than selling back after the semester is over. Even if the students throw it out or sell it, they can always look it up on the net again. Or perhaps today's students mostly use online sources to begin with. (Chances are your students might be using this book even if you are requiring another one.)*
 
*Another aim of the book is to allow modification and customization for a specific purpose if necessary. If you do modify the book, mark it prominently as such to avoid confusion. This aspect is important for the longevity of the book as well. The book can be updated, fixed, and modified even if I happen to drop off the face of the earth. You do not have to depend on any publisher being interested as with traditional textbooks.*

*Finally, errata are fixed promptly. No need to wait several years for a new edition. Every once in a while I may make some major addition and a new major version (edition), and then in between as errata are fixed I make minor version updates (like a corrected printing) usually once or twice a year, depending on the errata discovered. Exercise, chapter, and section numbers are preserved as much as humanly possible. What's added is added at the end with new numbers, so the book is generally compatible even if students (or the instructor) have an older printed copy. The minor updates are totally interchangeable and have very minimal changes, essentially nothing new.*

**Project websites:**
* https://www.jirka.org/diffyqs/
* https://github.com/jirilebl/diffyqs

---

**Related materials:**
* [Differential Equations (MIT 18.03) - Video lectures 2003](https://academictorrents.com/details/1bd4f7e3b3c0505869e5c1b54e98af54b125d05e)
* [Differential Equations (MIT 18.03) - Worked examples 2011](https://academictorrents.com/edit/6c3432a82526a1f25ca0edc4e9f09254da66aeb2)
* [Differential Equations (MIT 18.03) - Supplementary notes 2010](https://academictorrents.com/details/1d3ced525d5c5bfbcaa71e176c371c373e4122dc)

---

**Table of contents:**

* Introduction
* Chapter 1. First-order equations
* Chapter 2. Higher-order linear ODEs
* Chapter 3. Systems of ODEs
* Chapter 4. Fourier series and PDEs
* Chapter 5. More on eigenvalue problems
* Chapter 6. The Laplace transform
* Chapter 7. Power-series methods
* Chapter 8. Nonlinear systems
* Appendix A. Linear algebra 
},
keywords= {Math, Maths, mathematics, calculus},
terms= {This work is dual licensed under a Creative Commons Attribution-Noncommercial-Share Alike 4.0 License (https://creativecommons.org/licenses/by-nc-sa/4.0/) and Creative Commons Attribution-Share Alike 4.0 License (https://creativecommons.org/licenses/by-sa/4.0/). You can use, print, copy, and share this book as much as you want. You can base your own book/notes on these and reuse parts if you keep the license the same (that is, as long as you use at least one of the two licenses). },
license= {https://creativecommons.org/licenses/by-nc-sa/4.0/},
superseded= {}
}