Refactor mathimpl a bit and add docstrings
Refactor mathimpl a bit and add docstrings

cpcloud/numba,jriehl/numba,numba/numba,gdementen/numba,stuartarchibald/numba,stefanseefeld/numba,stonebig/numba,IntelLabs/numba,cpcloud/numba,jriehl/numba,pombredanne/numba,ssarangi/numba,pombredanne/numba,IntelLabs/numba,numba/numba,numba/numba,IntelLabs/numba,pombredanne/numba,pombredanne/numba,seibert/numba,jriehl/numba,stefanseefeld/numba,stuartarchibald/numba,stuartarchibald/numba,stuartarchibald/numba,GaZ3ll3/numba,pitrou/numba,IntelLabs/numba,GaZ3ll3/numba,seibert/numba,cpcloud/numba,seibert/numba,GaZ3ll3/numba,pitrou/numba,ssarangi/numba,GaZ3ll3/numba,numba/numba,ssarangi/numba,ssarangi/numba,seibert/numba,cpcloud/numba,jriehl/numba,sklam/numba,gdementen/numba,gmarkall/numba,sklam/numba,stefanseefeld/numba,gdementen/numba,gmarkall/numba,sklam/numba,stefanseefeld/numba,GaZ3ll3/numba,stefanseefeld/numba,IntelLabs/numba,numba/numba,stuartarchibald/numba,gdementen/numba,gmarkall/numba,gdementen/numba,gmarkall/numba,stonebig/numba,pitrou/numba,stonebig/numba,sklam/numba,gmarkall/numba,jriehl/numba,pombredanne/numba,ssarangi/numba,cpcloud/numba,seibert/numba,stonebig/numba,stonebig/numba,pitrou/numba,sklam/numba,pitrou/numba