For series_sin instead of dividing by

Timings are 5570ms vs 1589ms for piranha vs flint

`i!`

, I tried multiplying by `prod(j!)/i!`

and then dividing the whole result by `prod(j!)`

Timings are 5570ms vs 1589ms for piranha vs flint

1000

and this is with the PR and nothing else? or also @rwst's patch?

This is only useful when the input to sin has all rationals with den=1

with @rwst 's patch

ok, I am curious to see what happens in conjunction with the other modifications

For something like

`sin((x+x^2)/123)*cos((x+x^2)/123)`

timings are 245,203 ms vs 3593ms
good to know, I hope the situation for this case improves when the pre-normalisation of the fractions is disabled

need to go get some sleep, I'll be back in a few hours

I'll merge the PR tomorrow

@isuruf I merged the PR here https://github.com/bluescarni/piranha/tree/small_series I will be pushing and testing other small series optimisations here as well

@rwst thanks, I will be testing against it

@isuruf I changed slightly the logic of your original commit, extended to sub and operations with integers, and added testing bits

bluescarni/piranha@e7008c7