Add and fix some documentations and a minor optimization

[lovesh]

Documentation updates

• Code comment describing what some of the symbols from the paper are renamed to
• Fix name and comment on a test

Minor optimization reducing the input size to an MSM

Signed-off-by: lovesh lovesh.bond@gmail.com

[Pratyush]

Could you add a CHANGELOG entry, and then we can merge this!

[lovesh]

@Pratyush Done.