Opened 3 years ago

Closed 3 years ago

#28072 closed defect (fixed)

Issue in calculus on manifolds with incomplete set of transition maps

Reported by: egourgoulhon Owned by:
Priority: major Milestone: sage-8.9
Component: geometry Keywords: manifolds, scalar field
Cc: tscrim Merged in:
Authors: Eric Gourgoulhon Reviewers: Travis Scrimshaw
Report Upstream: N/A Work issues:
Branch: 7d13b13 (Commits, GitHub, GitLab) Commit: 7d13b136fc258009992a042953ffdf3085edecf0
Dependencies: Stopgaps:

Status badges

Description (last modified by egourgoulhon)

In Sage 8.8, we have 

sage: M = Manifold(2, 'M')
sage: X.<x,y> = M.chart()
sage: Y.<u,v> = M.chart()
sage: X_to_Y = X.transition_map(Y, [x+y, x-y])
sage: f = M.scalar_field({X: x*y})
sage: g = M.scalar_field({Y: u*v})
sage: f + g
...
KeyError: (Chart (M, (u, v)), Chart (M, (x, y)))

If one initializes the inverse transition map, things are OK: 

sage: X_to_Y.inverse()
Change of coordinates from Chart (M, (u, v)) to Chart (M, (x, y))
sage: f + g
Scalar field on the 2-dimensional differentiable manifold M
sage: _.display()
M --> R
(x, y) |--> x^2 + x*y - y^2
(u, v) |--> 1/4*u^2 + u*v - 1/4*v^2

But even without knowing the inverse transition map, Sage should be capable to compute the value of f + g, with the result expressed in the chart X only.

Change History (4)

comment:1 Changed 3 years ago by egourgoulhon

  • Authors set to Eric Gourgoulhon
  • Branch set to public/manifolds/incomplete_transition_map-28072
  • Cc tscrim added
  • Commit set to 7d13b136fc258009992a042953ffdf3085edecf0
  • Description modified (diff)
  • Status changed from new to needs_review

New commits:

​7d13b13Fix issue with incomplete set of transition maps (Trac #28072)

comment:2 Changed 3 years ago by tscrim

  • Reviewers set to Travis Scrimshaw
  • Status changed from needs_review to positive_review

LGTM.

comment:3 Changed 3 years ago by egourgoulhon

Thanks for the review!

comment:4 Changed 3 years ago by vbraun

  • Branch changed from public/manifolds/incomplete_transition_map-28072 to 7d13b136fc258009992a042953ffdf3085edecf0
  • Resolution set to fixed
  • Status changed from positive_review to closed
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