APEX Calculus is written by me, Gregory Hartman, Associate Professor of Mathematics at Virginia Military Institute. Contributions were made by Troy Siemers and Dimplekumar Chalishajar of VMI and Brian Heinold of Mount Saint Mary's University. Jennifer Bowen of the College of Wooster edited the text. It is copyrighted under the Creative Commons Attribution - Noncommercial (BY-NC) License.

Thank you: Thanks to Troy, Brian and Dimple for their contributions and to Jennifer for reading through so much material. Thanks to Troy, Lee Dewald, Dan Joseph, Meagan Herald, Bill Lowe and other faculty of VMI who have given me numerous suggestions and corrections based on their experience with teaching from the text. (Special thanks to Troy, Lee & Dan for teaching Calc III as I wrote the Calc III material.) Thanks to Randy Cone for encouraging his tutors of VMI's Open Math Lab to read through the text and check the solutions, and thanks to the tutors for spending their time doing so. A very special thanks to Kristi Brown and Paul Janiczek who took this opportunity far above & beyond what I expected, meticulously checking every solution and carefully reading every example. Their comments have been extraordinarily helpful. I am blessed to have so many people give of their time to make this book better.  

The rest of this page describes how APEX Calculus was written. This is likely an uninteresting read except for those who are thinking of writing their own open text.

The seeds of APEX Calculus were planted as I wrote Fundamentals of Matrix Algebra for my Matrix Algebra course and Troy wrote An Introduction to MATLAB and Mathcad for his students learning mathematical software. We realized that writing texts was rewarding personally and professionally and were amazed more people were not doing this.

Troy, a colleague Daniel Joseph and I conceived of the APEX model, wherein multiple people collaborate on writing a text and lightening everyone's load. I decided to lead the writing of the first APEX-model book, a text on Linear Algebra. Later, our focus shifted to writing a Multivariable Calculus book, enlisting the help of two others from other Virginia schools. 

In the Fall of 2011, VMI offered grants to faculty to support projects that would significantly change education. With Troy's encouragement, I applied for grant money to buy course releases so I could devote significant time to writing. Many of my colleagues in the local MAA Section were interested in participating in the project, and I wrote the potential of their support in my grant application. To make the biggest impact, we decided that our text should be Calculus (and not just the multivariable portions).

I was awarded the grant and immediately began planning the text. I spent a lot of time determining how the book would look, including font choice, what the figures would look like and where they would be located, and a visual method for indicating where examples began & ended. Much of this was in line with features of traditional texts. Troy was intentional in thinking of something "new" we could do that other texts wouldn't, which led us to including the Notes space at the bottom of each page.

When I announced to my interested colleagues that I had received course releases to lead the project, most congratulated me and politely backed out. I understood why they couldn't participate: they were busy, just as I was. The big difference between us was that I had two course releases and they didn't.

In the Spring of 2012, I made great progress, writing chapters 1 through portions of 6. Troy helped by writing two sections, and Brian Heinold also contributed a few sections. Jennifer Bowen was editing the material, making suggestions and offering much appreciated compliments. In the Fall of 2012, VMI used these completed chapters to teach our Calc 1 course and I continued to write. By the Spring of 2013, I had completed all of the Calc 2 material and we were now teaching both Calc 1 and 2 with our newly completed text.

I had also been awarded one more course release. My dean and the VMI Board were impressed with how much had been accomplished and gave me the additional course release to help me finish. So during the Spring of 2013 I wrote much of the Calc 3 material. But not all. I continued to write over part of the summer, but went into the Fall of 2013 without a full Calc 3 text. We as a department were committed to using this text, as by this time our students had known no other calculus book. So I taught Calc 3 with 3 colleagues and wrote furiously, completing the text "just in time." My colleagues were incredibly patient and helpful during this time. Dimplekumar Chalishajar also contributed a few sections.

Somewhere in the midst of writing it became clear, without formal declaration, that this was "my" text. It was intended to be a collaborative effort, with many authors contributing and critiquing each other's work as we collectively worked toward completion of a text. (Lots of "c" words in that sentence.) This is not how it turned out. APEX Calculus was my book and the contributors were ... contributing to my work. I edited, sometimes heavily, the sections they submitted without their care or concern. They wrote to help me out (and they did!), not to be officially known as a "coauthor." 

APEX Calculus Version 1.0 was "released" for the Fall of 2013, consisting of chapters 1 - 8. During this academic year, I finished chapters 9 - 13 and also added material to the previously completed sections, most notably chapters 6 and 8. I also fixed lots of typos my colleagues found. In the Fall of 2014, Version 2.0 was released; Version 3.0 was released June, 2015; Version 4.0 was released in May, 2018.