GSoC 2020 - Week 8

Key highlights of this week’s work are:

• Fixed incorrect limit evaluation related to LambertW function

  • This was a minor bug fix. We added the _singularities feature to the LambertW function so that its limit gets evaluated using the meromorphic check already present in the limit codebase.
    
    

• Fixed errors in assumptions when rewriting RisingFactorial / FallingFactorial as gamma or factorial

  • This was a long pending issue. The rewrite to gamma or factorial methods of RisingFactorial and FallingFactorial did not handle all the possible cases, which caused errors in some evaluations. Thus, we decided to come up with a proper rewrite using Piecewise which accordingly returned the correct rewrite depending on the assumptions on the variables. Handling such rewrites using Piecewise is never easy, and thus there were a lot of failing testcases. After spending a lot of time debugging and fixing each failing testcase, we were finally able to merge this.

This marks the end of Phase-2 of the program. I learnt a lot during these two months and gained many important things from my mentors.