points by StilesCrisis 4 days ago | 0 comments
The very first formula in the text, explicitly described as "as simple as possible," names its variable ê1 with no explanation given. I think this paper needs another pass.
[–] mkl 4 days ago
It's just giving a vector a name. It also names ê₂. These particular names are very standard and familiar to most people who've met vectors before.
You can look at those vectors and see that the position of the 1 is the subscript, without explanation. The ^ could do with an explanation that it means unit vector, but if you've met vectors before you likely know that (maybe that's elsewhere in the book, but a quick search didn't find it).
[–] nhatcher 4 days ago
That's absolutely standard notation for a unit basis vector. I haven't read the prerequisites carefully, so if it addressed to the general public maybe?
It is perhaps addressed to a different crowd?
[–] StilesCrisis 4 days ago
For a book promising to introduce the basics from first principles, it wouldn't hurt to explain arbitrary diacritical markings.
[–] totetsu 4 days ago
It’s not okay to be forgetful of maths anymore. Whats a dot product, whats a unit vector, how does matrix multiplication work..
[–] mkl 4 days ago
It's fine to be forgetful of maths that you're not actively using. (I am speaking as a mathematician.) It's also easier than ever to get a quick reminder or introduction, e.g. for this Google something like [what does e1 with ^ on the e mean], or [standard basis vector] from earlier in the sentence, or ask another AI.
[–] StilesCrisis 4 days ago
I was never actually taught ê as unit vector notation. I did game development for years and am quite familiar with 3D math but a lot of formal math notation is very foreign to me.
[–] apricot 4 days ago