One of the things that never got migrated to the PreTeXt version is the preface.
I've just taken care of that (I think).
It will need some updating (mostly by Greg, but maybe any of us can say a bit more about the PreTeXt version) but it's better than nothing.
I also added in the APEX logo provided by Greg on another thread on here.
One concern: in an earlier cleanup commit, Alex took the overall introduction to the book (which had been in the text for the first chapter) and moved it to a preface section in the frontmatter.
That belongs after the preface I've just added, and after the acknowledgements.
Can it remain a preface?
Can we have
<preface>
<acknowledgements>
<preface>?
We will soon find out, I suppose!
No pull request yet, because I wasn't paying attention, and built the branch that it's in off of my branch for changing the indexing in Riemann sums, instead of the main branch. So I will wait until that's merged.