Make legendre_P() a GinacFunction

[rwst]

Pynac-0.7.16 offers legendre_P(). The performance increase:

                            Python+Pari        Pynac
                            -----------        -----
sage: _=legendre_P(10,x)      510 µs           29 µs
sage: _=legendre_P(100,x)     2.3 ms           290 µs
sage: _=legendre_P(1000,x)    28 ms            3.5 ms
sage: _=legendre_P(10000,x)   1.1 s            110 ms
sage: _=legendre_P(50000,x)   30 s             2.1 s

overall a speedup of a comfortable order of magnitude.

Depends on #24668

Component: performance

Author: Ralf Stephan

Branch/Commit: 6c0ef30

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/24553

[rwst]

Branch: u/rws/make_legendre_p___a_ginacfunction

[rwst]

New commits:

6c0ef30

24553: Make legendre_P() a GinacFunction

[rwst]

Commit: 6c0ef30

[tscrim]

comment:3

Ready for review?

[rwst]

Dependencies: pynac-0.7.16

[rwst]

comment:4

It will not work without pynac-0.7.16.

[rwst]

Changed dependencies from pynac-0.7.16 to #24668

[rwst]

Author: Ralf Stephan

[rwst]

comment:6

Replying to @tscrim:

Ready for review?

Yes, please.

[tscrim]

comment:7

LGTM.

[tscrim]

Reviewer: Travis Scrimshaw

[rwst]

comment:8

Thanks!

[vbraun]

Changed branch from u/rws/make_legendre_p___a_ginacfunction to 6c0ef30