explain the performance improvement

explain the change of the extension polynomial

fix roll and copy

add copy and roll for u31ext

add the fromaltstack and toaltstack for ext

remove nightly dependency

update the README

update the README

update readme and the method

add mul by constant

Implement u31_ext multiply by u31 (#1)

use a larger lookup table

progress

work in progress

update the benchmark

add u31_neg

update the dependency to match BitVM

Update README.md

window method

reword

double karatsuba

link

update the karatsuba

improve the reduction

reorg files

update the performance

u31 and u31ext

add u31

Initial commit