Tensor Fields and Sections: Naming Consistencies

[gh-DeRhamSource]

This ticket is part of the metaticket #28519 and consists of:

• copies apply no name from the original in any case
• copy method with individual naming
• (right) multiplication with a scalar field f yields to the name f*a and the LaTeX name f \cdot a for any tensor/section (or scalar) field a

[git]

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

​99c392c

Copy and multiplication names

[git]

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

​b3e0468

MixedForm copies apply names

[gh-DeRhamSource]

Actually, what do you prefer? Should copies apply the names from the original or not?

I think, at least it must be consistent...

[egourgoulhon]

Replying to gh-DeRhamSource:

Actually, what do you prefer? Should copies apply the names from the original or not?

I don't have a strong opinion on that. Travis?

[tscrim]

Replying to egourgoulhon:

Replying to gh-DeRhamSource:

Actually, what do you prefer? Should copies apply the names from the original or not?

I don't have a strong opinion on that. Travis?

I might say no just because copies are meant to be modified, so they should have different names. However, like Eric, this is not a strong opinion. Actually, is there a mechanism to change the name?

[egourgoulhon]

Replying to tscrim:

Replying to egourgoulhon:

I might say no just because copies are meant to be modified, so they should have different names. However, like Eric, this is not a strong opinion.

Thanks for your answer.

Actually, is there a mechanism to change the name?

Yes there is the method set_name().

[tscrim]

Replying to egourgoulhon:

Replying to tscrim:

Actually, is there a mechanism to change the name?

Yes there is the method set_name(). One could also pass the (possible) new name as an argument to copy(). There are a few examples (2 actually) of copy() taking some arguments in Sage library.

Hmm...in that case I probably would say to not copy the name (with a .. WARNING:: (perhaps .. NOTE::) block about that) and have copy() take an optional argument for the (latex) name.

[git]

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

​e4470b5	Merge branch 'develop' into t/28564/tensor_fields__consistent_naming
​47e2f51	copy method with naming
​f55b881	Doctest adapted

[gh-DeRhamSource]

That's strange. I cannot observe merge conflicts. What's the matter?

[egourgoulhon]

Replying to gh-DeRhamSource:

That's strange. I cannot observe merge conflicts. What's the matter?

It's because your develop branch is still 9.0.beta2 (this is what I see from the commit e4470b5). You should update to 9.0.beta3.

[git]

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

​f85de87

Merge branch 'develop' into t/28564/tensor_fields__consistent_naming

[gh-DeRhamSource]

That should be it.

[egourgoulhon]

As revealed by the patchbot, there is one failed doctest:

sage -t --long src/sage/manifolds/differentiable/tensorfield.py
**********************************************************************
File "src/sage/manifolds/differentiable/tensorfield.py", line 260, in sage.manifolds.differentiable.tensorfield.TensorField
Failed example:
    s = f*t; s  # long time
Expected:
    Tensor field of type (0,2) on the 2-dimensional differentiable
     manifold S^2
Got:
    Tensor field f*t of type (0,2) on the 2-dimensional differentiable manifold S^2

[egourgoulhon]

Another point: the introduction of the treatment of the names in FreeModuleTensor._rmul_() is a valuable enhancement, thanks. However, I wonder about the \cdot in the LaTeX output: _rmul_() deals with the left multiplication of a module element by an element of the base ring and in most textbooks, this is denoted without any multiplication symbol, i.e. as \lambda x, where \lambda is the ring element and x is the module element. This is certainly true in the two textbooks that we quote regarding free modules:

• R. Godement : *Algebra* [God1968]_
• S. Lang : *Algebra* [Lan2002]_

Granted: ​Wikipedia article uses the dot...

[git]

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

​eb92e6a

Doctest fixed

[gh-DeRhamSource]

Mhm. I partially agree with you. In practice, the notation is certainly inconvenient and everything is clear by choosing correct letters, but in this case I guess everything has to be rigorous. The \cdot makes unambiguously clear that an operation was performed on both elements.

The doctest is fixed. This is indeed a doctest error, but strangely it didn't occur to me in the first place.

[egourgoulhon]

Replying to egourgoulhon:

Granted: ​Wikipedia article uses the dot...

On the other hand, the dot-free notation is used in ​Wikipedia article 'Vector space'.

Travis, do you have an opinion on that? In particular, do we have other modules in Sage with named elements? If so, what is the adopted convention? (I think we should be consistent there).

[tscrim]

Replying to egourgoulhon:

Replying to egourgoulhon:

Granted: ​Wikipedia article uses the dot...

On the other hand, the dot-free notation is used in ​Wikipedia article 'Vector space'.

Travis, do you have an opinion on that? In particular, do we have other modules in Sage with named elements? If so, what is the adopted convention? (I think we should be consistent there).

I don't know of any other place in Sage where we do something like this. Although at \cdot is much better than a period for an action IMO ^^;;.

[egourgoulhon]

Replying to tscrim:

Replying to egourgoulhon:

Replying to egourgoulhon:

Granted: ​Wikipedia article uses the dot...

On the other hand, the dot-free notation is used in ​Wikipedia article 'Vector space'.

Travis, do you have an opinion on that? In particular, do we have other modules in Sage with named elements? If so, what is the adopted convention? (I think we should be consistent there).

I don't know of any other place in Sage where we do something like this. Although at \cdot is much better than a period for an action IMO ^^;;.

OK. Let us keep the \cdot then...

[egourgoulhon]

We are almost done here I think. One very last thing: you should modify the ticket description, to take into account the change in copy().

[git]

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

​5b2eee2

'copy' with individual naming

[gh-DeRhamSource]

New commits:

​5b2eee2

'copy' with individual naming

[egourgoulhon]

Thanks.

[vbraun]

Merge conflict

[git]

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

​38aa7f5

Merge branch 'develop' into t/28564/tensor_fields__consistent_naming

[gh-DeRhamSource]

That should be it. Please check.

[tscrim]

Replying to gh-DeRhamSource:

That should be it. Please check.

Did you get a merge conflict when merging in beta4? Otherwise, there is a merge conflict with the upcoming beta5.

[gh-DeRhamSource]

Replying to tscrim:

Replying to gh-DeRhamSource:

That should be it. Please check.

Did you get a merge conflict when merging in beta4?

Yes.

[tscrim]

Great, thanks.

[vbraun]

Merge conflict, possibly #28578... just wait for beta5

[git]

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

​9d39cb5

Merge branch 'develop' into t/28564/tensor_fields__consistent_naming

[fbissey]

Doctest failure

sage -t --long /usr/lib/python3.7/site-packages/sage/manifolds/differentiable/tensorfield.py
**********************************************************************
File "/usr/lib/python3.7/site-packages/sage/manifolds/differentiable/tensorfield.py", line 269, in sage.manifolds.differentiable.tensorfield.TensorField
Failed example:
    s = f*t.restrict(U); s
Expected:
    Tensor field of type (0,2) on the Open subset U of the 2-dimensional
     differentiable manifold S^2
Got:
    Tensor field f*t of type (0,2) on the Open subset U of the 2-dimensional differentiable manifold S^2

One such doctest was fixed in the same file at line 263 but this one was missed.

[git]

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

​67e5cdc

Trac #28564: One line doctest error fixed

[git]

Branch pushed to git repo; I updated commit sha1 and set ticket back to needs_review. New commits:

​5dd53b0

Trac #28564: raw strings for LaTeX code

[gh-DeRhamSource]

Now, everything must be fine, I guess.

[gh-DeRhamSource]

Please give it a positive review, again. Sorry for this trivial mistake in the first place.

[egourgoulhon]

Thanks for the fix.

[git]

Branch pushed to git repo; I updated commit sha1 and set ticket back to needs_review. New commits:

​34f2fa1

Trac #28564: Merge branch 'develop' into t/28564/tensor_fields__consistent_naming

[gh-DeRhamSource]

Please give it a positive review again...

[egourgoulhon]

The 9.0.beta6 patchbot is all green.