Free Linear Algebra textbook
Author here.  I like to look over HN during breakfast, so a surprise this morning. I appreciate folks's kind words.Can I slide in the back story?  The course I had as an undergrad was very computational.  Matrix multiplication is associative because the indices combine in this way and then you distribute the a_i,j's, etc.  I could follow it line-by-line but I didn't feel any real understanding.In grad school I learned that it all makes beautiful sense. So when I started teaching, I wanted an approach that conveyed the sense.  I adopted a book that is a great book, very clear and clean, but students did not understand it.  They were good students, but they just were not ready.  They needed more examples, and by-hand calculations, for instance.I resolved to find a presentation that helped bring them to where they would be ready, or at any rate formed part of a deliberate effort by an undergrad program to work on maturity.  I didn't find a book that worked for me, so I wrote one.So although there are a lot of examples and a lot of computation, like the text I had as an undergrad, this development keeps trying to direct the attention of students toward the understanding that they get from higher-level ideas.I often see online where someone asks "What is the right book for XXX?"  It seems to me that often there is no one best.  Often, it depends on the audience.  For the students that I see, this approach accomplishes a lot, it seems to me.