[curves] ECC introduction: point addition on simple Weierstrass form

[Dominik Pantůček]

Hi curves fans,
> Speaking of slowly going through all the basics, I produced another
> article[2] and accompanying video[3] - this time about point at
> infinity. Truth is, I am not satisfied with this one and I am thinking
> about creating another one showing the actual intersections at point at
> infinity on the projective plane.
I have put some more thought in explaining the point at infinity in the
projective plane and created a visualization using stereographic
projection onto a sphere[1]. The accompanying article[2] wouldn't
probably be of much interest here, but I am referencing it for the sake
of completeness. I would really appreciate any feedback as I am trying
to finalize the visualization framework (not there yet, but it is way
more polished than two months ago when I dug it out of git repository
after not touching it for about a year).

Cheers,
Dominik

[1] https://youtu.be/Hk0Fr-k7wmQ
[2]
https://trustica.cz/en/2018/04/05/elliptic-curves-point-at-infinity-revisited/