# Example for point addition using Jacobi transformation and small integers

This video explanation is great because it shows an example using small numbers, if it wasn't for that example my code would be wrong.

Still: the code takes 0.5 seconds to calculate 300 point doublings using 256 bit numbers. I found it's faster to do point addition or doubling using the Jacobi transformation or Weierstrass transformation but I can't find explanation examples using small numbers.

Can someone write an example of point addition using Jacobi transformation?

• Just a hint: you can take a look at the Explicit-Formulas Database. There's plenty of formulas for different form of elliptic curves. You can find point additions detailed as a succession of elementary operations (multiplication, squaring, addition over the base field). – user69015 Aug 12 '20 at 21:09
• I would really like an example using small numbers because learning from the equations alone would have made me calculate division incorrectly, substraction too. I predict similar mistakes will happen if I do the jacobi transformation – porente Aug 12 '20 at 21:28