Ticket #1400 (closed defect: fixed)

Opened 1 year ago

Last modified 3 months ago

[with patch, with negative review] QuadraticFields and ClassGroups

Reported by: ljpk Assigned to: was
Priority: minor Milestone: sage-3.1.2
Component: number theory Keywords: editor_craigcitro
Cc:

Description (Last modified by mabshoff)

SAGE can compute the class group of a quadratic field, but it has issues with computing the order of elements within that class group:

QF.<x>=QuadraticField(-39)
CF=QF.class_group()
CF(QF.ideal(1+x)).order()

gives

NotImplementedErrorTraceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/server2/sage_notebook/worksheets/ljpk/0/code/6.py", line 6, in <module>
    CF(QF.ideal(Integer(1)+x)).order()
  File "/home/sage10/", line 1, in <module>
    
  File "element.pyx", line 1190, in sage.structure.element.MultiplicativeGroupElement.order
  File "element.pyx", line 1130, in sage.structure.element.MonoidElement.multiplicative_order
NotImplementedError

Attachments

1400-quadratic_field_order.patch (2.6 kB) - added by AlexGhitza on 04/24/2008 07:47:55 PM.

Change History

12/04/2007 03:23:46 PM changed by mabshoff

  • description changed.
  • milestone set to sage-2.9.

04/24/2008 07:47:55 PM changed by AlexGhitza

  • attachment 1400-quadratic_field_order.patch added.

04/24/2008 07:49:10 PM changed by AlexGhitza

  • summary changed from QuadraticFields and ClassGroups to [with patch, needs review] QuadraticFields and ClassGroups.

The attached patch adds this functionality for fractional ideals and for their representatives in class groups.

04/27/2008 07:29:31 PM changed by ncalexan

  • summary changed from [with patch, needs review] QuadraticFields and ClassGroups to [with patch, with negative review] QuadraticFields and ClassGroups.

This uses an O(n) algorithm to compute orders. Don't we have generic BSGS O(sqrt(n)) that would be better here?

06/19/2008 09:26:45 PM changed by craigcitro

  • keywords set to editor_craigcitro.

08/27/2008 12:37:49 AM changed by mabshoff

  • status changed from new to closed.
  • resolution set to fixed.

Fixed via #3913.

Cheers,

Michael