Agreed - it's like they transplanted the "found in a rigorous math class" definition of a determinant. That's the one where the desired properties are the assumption and then you show that your preferred mechanical method of computation gives those properties. Usually there's a final step where you show the properties are enough to establish uniquemess.

None of those mathy steps occur in this book. There are just statements in boxes like "remember: all methods of computing the determinant give the same answer".

Honestly, looking at that section I'm having a hard time understanding how they justify the name "interactive linear algebra". The extent of my interactions is clicking on the arrow to expose the example.

The graphics are fine, but they aren't interactive like it says on the cover.

I do respect this, a lot:

> This textbook is exclusively targeted at Math 1553 at Georgia Tech. As such, it contains exactly the material that is taught in that class; no more, and no less: students in Math 1553 are responsible for understanding all visible content.