Remove silly LimitedPrecisionConstant class

[rwst]

brun fails horribly:

sage: brun.n()
NotImplementedError: brun is only available up to 41 bits
sage: brun?
NotImplementedError: brun is only available up to 41 bits
sage: brun??
NotImplementedError: brun is only available up to 41 bits

and this leads to sporadic failure of random_expr, falsifying patchbot test results.

CC: @kcrisman

Component: symbolics

Author: Ralf Stephan

Branch/Commit: 3e8d598

Reviewer: Karl-Dieter Crisman, Jeroen Demeyer

Issue created by migration from https://trac.sagemath.org/ticket/18255

[rwst]

Branch: u/rws/remove_silly_limitedprecisionconstant_class

[rwst]

Commit: 522c48b

[rwst]

Author: Ralf Stephan

[rwst]

New commits:

522c48b

18255: Remove silly LimitedPrecisionConstant class

[rwst]

comment:5

It makes patchbot runs useless. Certainly not minor.

[jdemeyer]

comment:6

Replying to @rwst:

It makes patchbot runs useless.

Really, why?

[rwst]

comment:7

As in the ticket description this leads to sporadic failure of random_expr.

[videlec]

comment:8

This is not a sporadic random failure

**********************************************************************
File "src/sage/symbolic/constants.py", line 28, in sage.symbolic.constants
Failed example:
    brun
Exception raised:
    Traceback (most recent call last):
    ...
    NameError: name 'brun' is not defined
**********************************************************************
1 item had failures:
   1 of  55 in sage.symbolic.constants
    [241 tests, 1 failure, 1.91 s]
----------------------------------------------------------------------
sage -t --long --warn-long 71.3 src/sage/symbolic/constants.py  # 1 doctest failed
----------------------------------------------------------------------

[7ed8c4ca-6d56-4ae9-953a-41e42b4ed313]

Changed commit from 522c48b to 3e8d598

[7ed8c4ca-6d56-4ae9-953a-41e42b4ed313]

Branch pushed to git repo; I updated commit sha1. New commits:

3e8d598

18255: remove doctest for removed code

[jdemeyer]

comment:11

Do you really want to remove the Brun constant itself? The problem is not with brun, the problem is with LimitedPrecisionConstant.

[rwst]

comment:12

So we add brun = whatever in all.py and get bug reports when a new decimal place is discovered?

[videlec]

comment:13

The Brun constant looks like something that we have no idea about excepted its existence... Even the decimals given on oeis do not seem to be proven exact. Do you have a reference for the associated computations? If not, I would rather remove it.

[jdemeyer]

comment:14

The decimals are certainly not proven correct, as far as I know it's even an open question whether brun < 2.

So I get your point...

[kcrisman]

comment:16

Having it in Sage is nice with regard to the Pentium bug, though... (that is, demonstrating even wacky theory has applications).

[videlec]

comment:17

Replying to @kcrisman:

Having it in Sage is nice with regard to the Pentium bug, though... (that is, demonstrating even wacky theory has applications).

But then it should not be called brun. What about brun_as_conjectured_by_XYZ? If we had any way to compute it (even very slow) I would be happy to keep it.

[jdemeyer]

comment:18

Replying to @videlec:

But then it should not be called brun. What about brun_as_conjectured_by_XYZ?

It's not a conjecture, it's an estimate.

[kcrisman]

comment:19

I wonder how many failures it would make - running TestSuite would be instructive, if scary.

The decimals are certainly not proven correct, as far as I know it's even an open question whether brun < 2.

Interesting! (Do you have a reference? I can only find references to estimates using twin primes < 10 to the something.)

Are there any (other?) constants known to some number of bits only of potential interest? I bet there are, but maybe it's not worth keeping the class around for that.

(Deprecation? Just asking.)

[rwst]

comment:20

Replying to @kcrisman:

(Deprecation? Just asking.)

Wrong question. It should rather read: will I review and set positive if you add deprecation?

[kcrisman]

comment:21

No, because I don't feel qualified to address the question of whether this class should exist. I asked about deprecation because this would be a rather unusual case where the class may not have been meaningful enough to keep around even in deprecated format (bugs aren't deprecated).

[rwst]

comment:22

If I understand correctly you are of the opinion that deprecation is likely not necessary. Well, I agree.

[kcrisman]

comment:23

On the other hand, perhaps someone should check first whether this is in other systems (think mission statement). I'm not sure whether this indicates anything about it in Mma or not.

[rwst]

comment:24

You mean they have a named string that contains "~2"? Let's pretend they have, would we want to copy it?

[kcrisman]

comment:25

Well, I just meant whatever they did have - perhaps just for reference. But you are probably right, the whole class is probably not (currently) useful. (But it could be later - maybe we could keep the class, not the constant, in as commented? But again, I'm not feeling qualified to give positive review to any of that - I would certainly support e.g. Jeroen if he did, though.)

[jdemeyer]

comment:26

Replying to @kcrisman:

maybe we could keep the class, not the constant

The class is buggy, which was the original reason that this ticket was created. If you remove the constant and keep the class, you are just hiding that problem.

[kcrisman]

comment:27

I meant just to comment it out but keep it there in commented state so it would be easier for someone to fix. But I don't really care that much, whatever @jdemeyer says is fine with me, because of the unusual case. Where was this even added (rhetorical question)?

[jdemeyer]

Reviewer: Karl-Dieter Crisman, Jeroen Demeyer

[rwst]

comment:29

Thanks for the review!

[vbraun]

comment:30

Merge conflict

[rwst]

comment:31

Replying to @vbraun:

Merge conflict

Where? Develop merges cleanly.

[kcrisman]

comment:32

Merge conflict

Where? Develop merges cleanly.

Yeah, Volker, the branch is green... can you at least let us know which ticket?

[vbraun]

comment:34

possibly with something that I unmerged, or maybe wrong ticket

[vbraun]

Changed branch from u/rws/remove_silly_limitedprecisionconstant_class to 3e8d598