Opened 10 years ago

Last modified 7 years ago

#13661 new enhancement

accuracy problem in matrix_mod_pn for Eisenstein extensions of padics

Reported by: Julian Rüth Owned by: David Roe
Priority: minor Milestone: sage-6.4
Component: padics Keywords: days71
Cc: Merged in:
Authors: Julian Rueth Reviewers:
Report Upstream: N/A Work issues:
Branch: u/saraedum/accuracy_problem_in_matrix_mod_pn_for_eisenstein_extensions_of_padics (Commits, GitHub, GitLab) Commit: 956f12477e66fa1f2568e910e1f1c6a97d2d7783
Dependencies: #13659 Stopgaps:

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Description

Currently, the accuracy of the matrix returned by matrix_mod_pn() in padic extension rings is probably too small:

sage: R=ZpCA(3,5)
sage: S.<a> = R[]
sage: L.<a>=R.extension(a^2-3)
sage: t=a.add_bigoh(2)
sage: t.matrix_mod_pn()
[0 1]
[0 0]
sage: (t*a)._ntl_rep_abs() # but t*a is not zero
([3], 0)

I think it would be better to return the following:

[0 1]
[3 0]

Of course, the "1" is not known to precision O(3^2) but I think it is better to leave it to the caller to strip away the digits that are not wanted.

The attached patch increases the precision to the maximal precision of any of the entries of the matrix.

Attachments (1)

trac_13661.patch (19.6 KB) - added by Julian Rüth 10 years ago.

Download all attachments as: .zip

Change History (7)

Changed 10 years ago by Julian Rüth

Attachment: trac_13661.patch added

comment:1 Changed 9 years ago by Jeroen Demeyer

Milestone: sage-5.11sage-5.12

comment:2 Changed 9 years ago by For batch modifications

Milestone: sage-6.1sage-6.2

comment:3 Changed 8 years ago by For batch modifications

Milestone: sage-6.2sage-6.3

comment:4 Changed 8 years ago by For batch modifications

Milestone: sage-6.3sage-6.4

comment:5 Changed 7 years ago by Julian Rüth

Branch: u/saraedum/accuracy_problem_in_matrix_mod_pn_for_eisenstein_extensions_of_padics

comment:6 Changed 7 years ago by Julian Rüth

Commit: 956f12477e66fa1f2568e910e1f1c6a97d2d7783
Keywords: days71 added

New commits:

b87ff51Trac #13651: fixed a precision problem in _internal_lshift(), _ntl_rep_abs() of padics
c3875b9Merge branch 'develop' into t/13651/ticket/13651
9bb2a38http://trac.sagemath.org/raw-attachment/ticket/13659/trac_13659.patch
956f124Trac #13661: improved precision of matrix_mod_pn() and implemented matrix() for padics
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