RealBall: Document input aliasing

[cheuberg]

Add a warning that identical balls are assumed to represent the same number.

Depends on #17194

CC: @mezzarobba @fredrik-johansson

Component: numerical

Keywords: arb, RealBall

Author: Clemens Heuberger

Branch/Commit: 178f31e

Reviewer: Fredrik Johansson, Marc Mezzarobba

Issue created by migration from https://trac.sagemath.org/ticket/17809

[cheuberg]

Branch: u/cheuberg/rings/real_arb_doc

[cheuberg]

Commit: a445cf9

[cheuberg]

comment:2

As discussed in #17194, input aliasing should be documented.

---

Last 10 new commits:

aa39c10	#17194 RealBall: abstract away access to parent precision
d3e3998	#17194 RBF: add a precision() method
ce51f81	#17194 RBF: some more is_foo() and similar methods
1d92acf	Trac #17194: remove fmpr.pxd (partial revert of dd8933a)
5e41fcb	Trac #17194: remove imports of fmpr
4e7ec46	Trac #17194: is_zero, is_nonzero, is_exact
9e26152	Trac #17194: Implement comparisons
1196b57	Trac #17194: Fix RealBallField._an_element_
195a6ee	Trac #17194: Fix two broken references
a445cf9	Trac #17809: Document input aliasing

[fredrik-johansson]

comment:3

Is it obvious that "identical real balls" means the same Sage object, not different objects with identical values?

I guess the example should be z = x * x, not z = x^2, as the latter would be correct regardless.

[sagetrac-git]

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

178f31e

Trac #17809: x*x instead of x^2; mention RealBall objects

[sagetrac-git]

Changed commit from a445cf9 to 178f31e

[cheuberg]

comment:5

Replying to @fredrik-johansson:

Is it obvious that "identical real balls" means the same Sage object, not different objects with identical values?

I hope that it is clearer now.

I guess the example should be z = x * x, not z = x^2, as the latter would be correct regardless.

Of course, thank you, fixed.

[mezzarobba]

Reviewer: Fredrik Johansson, Marc Mezzarobba

[vbraun]

Changed branch from u/cheuberg/rings/real_arb_doc to 178f31e