Inaccuracy in symbolic series result on 32bit Linux

[rwst]

From #24838 comment:64

On 32-bit:

File "src/sage/functions/hypergeometric.py", line 148, in sage.functions.hypergeometric
Failed example:
    hypergeometric_U(2, 2, x).series(x == 3, 100).subs(x=1).n()
Expected:
    0.403652637676806
Got:
    0.403651580752398

Pynac is not involved in the numerics (hypergeometric_U is not a GinacFunction), so the hypothesis is that the expression before .n() is different with 32bit Linux pynac-0.7.22.

CC: @slel @sagetrac-tmonteil

Component: symbolics

Keywords: pynac, 32-bit, overflow

Author: Dave Morris

Branch/Commit: 689e08f

Reviewer: Matthias Koeppe

Issue created by migration from https://trac.sagemath.org/ticket/25688

[DaveWitteMorris]

Branch: public/25688

[DaveWitteMorris]

Commit: e8ee3fc

[DaveWitteMorris]

comment:2

This bug is fixed by the pynac patch in #31585. (So the inaccuracy in the sum is due to an arithmetic overflow.)

There is only new commit in the branch here. It just deletes the "known bug" tag from the doctest in src/sage/functions/hypergeometric.py that is in the description of this ticket.

---

New commits:

f1a99fa	trac 31585 pynac overflow patch
3fcf072	add doctests
fdde3d9	update pynac patch level
e8ee3fc	trac 25688 remove "known bug" tag

[DaveWitteMorris]

Changed keywords from none to pynac, 32-bit, overflow

[DaveWitteMorris]

Dependencies: #31585

[DaveWitteMorris]

Author: Dave Morris

[DaveWitteMorris]

Changed branch from public/25688 to public/25688r1

[DaveWitteMorris]

Changed commit from e8ee3fc to 73e975c

[DaveWitteMorris]

comment:4

Rebased on the new #31585 that eliminates a merge conflict.

---

New commits:

ecb99c8	trac 31585 pynac overflow patch
2d04fa4	add doctests
5a340ce	update pynac patch level
73e975c	trac 25688 remove "known bug" tag

[slel]

comment:5

Please rebase.

[DaveWitteMorris]

Changed branch from public/25688r1 to public/25688r2

[DaveWitteMorris]

Changed dependencies from #31585 to none

[DaveWitteMorris]

Changed commit from 73e975c to 689e08f

[DaveWitteMorris]

comment:7

Thanks for pointing out the merge conflict -- I hadn't noticed. I rebased on 9.4b6 (and deleted the dependency on #31585, which has already been merged).

---

New commits:

689e08f

trac 25688 remove "known bug" tag

[mkoeppe]

comment:10

Stalled in needs_review or needs_info; likely won't make it into Sage 9.5.

[mkoeppe]

Reviewer: Matthias Koeppe

[DaveWitteMorris]

comment:12

Thanks!

[vbraun]

Changed branch from public/25688r2 to 689e08f