Opened 2 years ago
Last modified 2 years ago
#28562 closed enhancement
Tensor Fields: Better Zero Treatment — at Version 14
Reported by:  ghDeRhamSource  Owned by:  

Priority:  major  Milestone:  sage9.0 
Component:  geometry  Keywords:  manifolds, tensor fields, scalar fields, mixed forms 
Cc:  tscrim, egourgoulhon  Merged in:  
Authors:  Michael Jung  Reviewers:  
Report Upstream:  N/A  Work issues:  
Branch:  u/ghDeRhamSource/better_zero_treatment (Commits, GitHub, GitLab)  Commit:  5d30100a5f1e4f809867dc5b564000cd2eddc9db 
Dependencies:  Stopgaps: 
Description (last modified by )
The zero element is always a special element. Therefore it should be treated as such. It should shorten computations and certainly be immutable. This ticket is devoted to that topic. (Similarly for the one element in the scalar field and mixed form algebra).
This ticket is part of the metaticket #28519.
Features
 an assertion error arises when altering the fixed elements zero or one
 a new attribute
_is_zero
is added to tensor fields and mixed form (similar to scalar fields)  computations with involved zero or one are shortened by using a simple check
 due to immutability of algebra elements, no copies are returned anymore for scalar field operations with zero or one
_is_zero
attribute is applied for copies
Change History (14)
comment:1 Changed 2 years ago by
 Branch set to u/ghDeRhamSource/better_zero_treatment
comment:2 Changed 2 years ago by
 Commit set to 9f91503dce5cbe14f52a6a77a34ae5a18f722f7d
 Description modified (diff)
comment:3 Changed 2 years ago by
 Commit changed from 9f91503dce5cbe14f52a6a77a34ae5a18f722f7d to 5094a3e802034be5916879a0225e5db2ccf9f0f8
Branch pushed to git repo; I updated commit sha1. New commits:
5094a3e  Return no copies for scalar field operations

comment:4 Changed 2 years ago by
 Description modified (diff)
comment:5 Changed 2 years ago by
 Description modified (diff)
comment:6 Changed 2 years ago by
 Commit changed from 5094a3e802034be5916879a0225e5db2ccf9f0f8 to 94cf06ab1ab5d87fbc8efc73d2688ea1c8c91267
Branch pushed to git repo; I updated commit sha1. New commits:
ca8dd88  Modules modified

892050e  FreeModuleLinearGroup: one treatment

1b96587  Zero treatment for FreeModules

b9c8287  AutomorphismField: zero treatment + MixedForm: set_restriction and add_comp_by_continuation

94cf06a  Mixed forms adapted to zero treatment + zero treatment for scalar fields

comment:7 Changed 2 years ago by
 Component changed from PLEASE CHANGE to geometry
 Status changed from new to needs_review
comment:8 Changed 2 years ago by
In MixedForm
, the zero (and one element for scalar fields) is treated separately. The code in there is not very beautiful, but it works for now. However, I plan to reorganize the code of mixed forms anyway (see #28519).
comment:9 Changed 2 years ago by
Also, I removed the _zero_element
attribute in the free modules and replaced it by a cached zero()
method. This is a better solution, I guess.
comment:10 Changed 2 years ago by
 Commit changed from 94cf06ab1ab5d87fbc8efc73d2688ea1c8c91267 to d949a13db29334e193ec9ff05fd7fe53deb65422
Branch pushed to git repo; I updated commit sha1. New commits:
d949a13  Minor code reduction

comment:11 Changed 2 years ago by
 Commit changed from d949a13db29334e193ec9ff05fd7fe53deb65422 to 5d30100a5f1e4f809867dc5b564000cd2eddc9db
Branch pushed to git repo; I updated commit sha1. New commits:
5d30100  More code reduction

comment:12 Changed 2 years ago by
The code snippet (see commits 5d30100 and d949a13) was quite messy. Well, it still is. At least it is readable and works for now. It gets a little bit better after merging (see #28519).
I will think about a better solution. But I guess, this requires a complete reorganization of the mixed form code.
comment:13 Changed 2 years ago by
 Status changed from needs_review to needs_info
After a bit of thinking, I came to the conclusion that the code snippet should be obsolete. (As a mathematician, I feel the urge to solve or fix a problem/error as soon as it occurs. Here: Doctest errors.) The thing is, due to our little discussion in #28519, the doctest must be flawed since mixed forms defined via preconstructed forms get altered.
So, I 'm going to delete this snippet again and modify the affected doctests.
Do you agree with my conclusion and procedure?
A further doctest change is devoted to #28578.
comment:14 Changed 2 years ago by
 Description modified (diff)
New commits:
'_is_zero' attribute added and modified