Robustify doctest in hyperbolic_geodesic.py

[rwst]

A doctest of the midpoint code in geometry/hyperbolic_space/hyperbolic_geodesic.py relies on exact reproduction of complicated symbolic expressions involving square roots. With recent changes in Pynac the representation of the result no longer matches, although it is mathematically identical.

The ticket changes the doctest to match results numerically.

Component: geometry

Author: Ralf Stephan

Branch/Commit: u/rws/robustify_doctest_in_hyperbolic_geodesic_py @ a90ce6a

Reviewer: Frédéric Chapoton

Issue created by migration from https://trac.sagemath.org/ticket/23582

[rwst]

Branch: u/rws/robustify_doctest_in_hyperbolic_geodesic_py

[rwst]

Author: Ralf Stephan

[rwst]

Commit: a90ce6a

[rwst]

New commits:

a90ce6a

23582: Robustify doctest in hyperbolic_geodesic.py

[fchapoton]

Reviewer: Frédéric Chapoton

[fchapoton]

comment:3

ok, looks good

[tscrim]

comment:4

I'm not completely sure about this. If it is mathematically identical, why not simply change the doctest with the new version of pynac? Should then all (sufficiently complicated) symbolic expressions output not be used for doctests? IMO, this makes the doctest less likely to catch errors and feels like a tiny step backwards in that regard.

[rwst]

comment:5

The change is no longer necessary because the mentioned change in Pynac didn't happen. I agree to make the ticket invalid.

However, let me point out that it is highly unlikely that a symbolic error would pass such a numeric test. Note that such numeric tests additionally test the FP evaluation code so it's more likely to catch bugs.