Undocumented items in reference manual

[olexandr-konovalov]

Tried to put cross-references into release overview for GAP 4.9.1 and they did not work:

#W WARNING: non resolved reference: rec(
  Attr := "DirectFactorsOfGroup",
  BookName := "ref" )
#W WARNING: non resolved reference: rec(
  Attr := "SemidirectDecompositions",
  BookName := "ref" )
#W WARNING: non resolved reference: rec(
  Attr := "NormalHallSubgroups",
  BookName := "ref" )
#W WARNING: non resolved reference: rec(
  BookName := "ref",
  Oper := "RootFFE" )
#W WARNING: non resolved reference: rec(
  BookName := "ref",
  Func := "IdOfFilter" )
#W WARNING: non resolved reference: rec(
  BookName := "ref",
  Func := "IdOfFilterByName" )
#I  File: manual.lab written.

Is there no documentation intentionally, or it's there but not hooked into the manual?

• DirectFactorsOfGroup
• SemidirectDecompositions
• NormalHallSubgroups
• RootFFE
• IdOfFilter
• IdOfFilterByName

[hulpke]

I think the first three were introduced in #379 and #591

RootFFE was never really documented. It got in because some finite field/basic number theory algorithms require a square root and was implements using the internal LogFFE. I think we now also have a method for larger FFE's that are represented differently.
I suspect it was always intended as a more internal function.

We probably should define what we consider as basic and as plausible operations for FFEs.

IdOfFilter (which sounds like Freudian analysis) is defined in filter.gi

[olexandr-konovalov]

@hulpke thanks. RootFFE is also a subject of #2131.