Re: Struggling with ellisogeny() and variable priorities

[Karim Belabas <Karim.Belabas@math.u-bordeaux.fr>]

* Jeroen Demeyer [2015-06-03 17:11]:
> I got confused because the variable number no longer indicates the priority.
> May I suggest a patch to help debugging? See attachment.

I understand the intent, but it would be too much (redundant!)
information for large multivariate objects.

I'd suggest to use variables() instead: its output is sorted by variable
priority.

  E = ...
  isog = ...
  yy = varhigher("yy");
  xx = varhigher("xx");
  ? variables([E, isog, 0, xx, yy])
  %5 = [xx, yy, x, y]

  E = ...
  isog = ...
  yy;
  xx;
  ? variables([E, isog, 0, xx, yy])
  %5 = [x, y, yy, xx]


I didn't bother to edit the argument list from ellisogeny (E, isog and 0
are less relevant...) : just wanted to show how you can see the list
of involved variables and their relative priorities.

Cheers,

    K.B.
--
Karim Belabas, IMB (UMR 5251)  Tel: (+33) (0)5 40 00 26 17
Universite de Bordeaux         Fax: (+33) (0)5 40 00 69 50
351, cours de la Liberation    http://www.math.u-bordeaux.fr/~kbelabas/
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