date:20180914

[sage-devel] Re: Change (bug or feature?) in 3d plots illustrating the reference manual

2018-09-14 Thread Volker Braun

I don't think there was a deliberate change. Rendering the jmol version 
requires java, which is an external dependency. There was also a bug in 
detecting java 10+ which is only fixed in Sage 8.4.beta4. The expected 
behavior is: If java is not installed or not properly found then the docs 
fall back to tachyon.



On Friday, September 14, 2018 at 4:09:28 PM UTC+2, Eric Gourgoulhon wrote:
>
> Hi,
>
> Between Sage 8.4.beta0 and 8.4.beta2, all 3d plots illustrating the 
> reference manual, like in this section 
> ,
>  
> have been changed to Tachyon-rendered images. Previously (in particular in 
> Sage 8.3),  they were png images reflecting the Jmol rendering.
> Is this a bug or a feature?
> Is this is a feature, note that it has the unfortunate effect of not 
> displaying things as the user will see them if she or he repeats the 
> command, since Jmol is the default viewer, not Tachyon. For instance, the 
> axes are loosing all graduation with Tachyon. Moreover some illustrations 
> are now broken: for instance, the "A 3d plot with a mesh" example of 
>
> http://doc.sagemath.org/html/en/reference/plot3d/sage/plot/plot3d/plot3d.html 
> does no longer show any mesh...
>
> Best wishes, 
>
> Eric. 
>
>
>

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Re: [sage-devel] Re: Py3, sorting vertices of graph

2018-09-14 Thread David Coudert

Two more:

   - #26284 : deals with comparability.pyx, digraph.py, 
   vertex_separation.pyx, cutwidth.pyx and connectivity.pyx
   - #26285: avoid comparison of vertex labels in MIPs of generic_graph.


Le vendredi 14 septembre 2018 13:43:37 UTC+2, David Coudert a écrit :
>
> I'm working on reducing the number of places where we explicitly compare 
> vertex labels.
> So far I'm focusing on MIPs.
>
>- #26274 : avoid comparison of vertex labels in MIP for file 
>`graph_coloring.py`
>- #26282 : avoid comparison of vertex labels in MIP for file `graph.py`
>
> More to come, and help for reviewing is more than welcome.
>

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[sage-devel] Change (bug or feature?) in 3d plots illustrating the reference manual

2018-09-14 Thread Eric Gourgoulhon

Hi,

Between Sage 8.4.beta0 and 8.4.beta2, all 3d plots illustrating the 
reference manual, like in this section 
,
 
have been changed to Tachyon-rendered images. Previously (in particular in 
Sage 8.3),  they were png images reflecting the Jmol rendering.
Is this a bug or a feature?
Is this is a feature, note that it has the unfortunate effect of not 
displaying things as the user will see them if she or he repeats the 
command, since Jmol is the default viewer, not Tachyon. For instance, the 
axes are loosing all graduation with Tachyon. Moreover some illustrations 
are now broken: for instance, the "A 3d plot with a mesh" example of 
http://doc.sagemath.org/html/en/reference/plot3d/sage/plot/plot3d/plot3d.html 

does no longer show any mesh...

Best wishes, 

Eric. 


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Re: [sage-devel] Re: Py3, sorting vertices of graph

2018-09-14 Thread David Coudert

I'm working on reducing the number of places where we explicitly compare 
vertex labels.
So far I'm focusing on MIPs.

   - #26274 : avoid comparison of vertex labels in MIP for file 
   `graph_coloring.py`
   - #26282 : avoid comparison of vertex labels in MIP for file `graph.py`
   
More to come, and help for reviewing is more than welcome.

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Re: [sage-devel] bug in interface to pari's nffactor

2018-09-14 Thread Dima Pasechnik

One could use 'git bisect' to narrow the problem down to a particular commit.
Just in case...
On Fri, Sep 14, 2018 at 12:16 PM Bruno Grenet  wrote:
>
> I've also tested on Ubuntu with gcc. Actually, I run new tests: The bug
> appears between 8.4beta2 (where it's still ok) and 8.4beta3. I'll try to
> find the the origin of the bug.
>
> Bruno
>
> Le 14/09/2018 à 10:38, Dima Pasechnik a écrit :
> > It might be a platform dependent bug. I guess John is working on some
> > Ubunty machine, using gcc.
> >
> > Please provide compiler details you're using, too...
> >
> >
> >
> > On Fri, Sep 14, 2018 at 9:25 AM Bruno Grenet  wrote:
> >> Which version of SageMath are you using? I am unable to reproduce the
> >> bug neither on 8.3beta7 nor on 8.4beta2.
> >>
> >> Bruno
> >>
> >> Example with 8.4beta2:
> >>
> >> sage: x = polygen(QQ)
> >> sage: f = x^20 - 15*x^19 + 70989*x^18 - 1646113*x^17 + 3890074283*x^16 -
> >> 199035549796*x^15 + 203804256639644*x^14 - 10
> >> : 657741285726487*x^13 + 9779630086245476401*x^12 -
> >> 457685358591718595073*x^11 + 211985887298317287648516*x^10 - 1
> >> : 3621268697129972225420327*x^9 + 3065457104886066023133986949*x^8 -
> >> 28110542105571309419720191704*x^7 + 345396659
> >> : 71867983088754678645580*x^6 -
> >> 1061445386217881235978009629856081*x^5 +
> >> 498395492968339432558541006017143039*x^4
> >> : - 15789239186368833250097534490638459475*x^3 +
> >> 1774782276941552319212370439848636475557*x^2 + 446933009353599830
> >> : 6027448264353195140536*x + 4277406750726325717327241436124994515881
> >> :
> >> sage: g = x^20 - 5*x^19 - 497395*x^18 + 43617925*x^17 + 92084825461*x^16
> >> - 13577322967760*x^15 - 7694013534722665*x^14
> >> :  + 1430561593275815035*x^13 + 321534254513790999596*x^12 -
> >> 70299145498412320125190*x^11 - 6894702144208513885815
> >> : 805*x^10 + 1786517983436254067840917780*x^9 +
> >> 72426826805051978098685836211*x^8 - 243381905572083104716625046705
> >> : 20*x^7 - 255231848841911020332784180965840*x^6 +
> >> 172908549561723112381441893500998965*x^5 - 10424385014144860101
> >> : 72621550211101919*x^4 -
> >> 555813027721813935650430329326884907050*x^3 +
> >> 6754721428610694790490649672796107843280*x
> >> : ^2 + 470810707124413968773034018937652067163520*x +
> >> 3896560262532181966922924457358135376686480
> >> :
> >> sage: Kf. = NumberField(f)
> >> sage: Kg. = NumberField(g)
> >> sage: embeddings = Kf.embeddings(Kg)
> >> sage: len(embeddings)
> >> 2
> >>
> >>
> >> Le 13/09/2018 à 16:16, John Cremona a écrit :
> >>> I have two polynomials of degree 20 defining the same number field (I
> >>> obtained the second from the first using pari's polredbest()
> >>> routine).  I am able to use is_isomorphic() to find isomorphisms
> >>> between them (there are 2) but embeddings() raises an error since
> >>> roots() does:
> >>>
> >>> sage: x = polygen(QQ)
> >>> sage: f = (x^20 - 15*x^19 + 70989*x^18 - 1646113*x^17 +
> >>> 3890074283*x^16 - 199035549796*x^15 + 203804256639644*x^14 -
> >>> 10657741285726487*x^13 + 9779630086245476401*x^12 -
> >>> 457685358591718595073*x^11 + 21
> >>> : 1985887298317287648516*x^10 - 13621268697129972225420327*x^9 +
> >>> 3065457104886066023133986949*x^8 - 28110542105571309419720191704*x^7 +
> >>> 34539665971867983088754678645580*x^6 - 106144538621788123597
> >>> : 8009629856081*x^5 + 498395492968339432558541006017143039*x^4 -
> >>> 15789239186368833250097534490638459475*x^3 +
> >>> 1774782276941552319212370439848636475557*x^2 +
> >>> 446933009353599830602744826435319514053
> >>> : 6*x + 4277406750726325717327241436124994515881)
> >>> sage: g = (x^20 - 5*x^19 - 497395*x^18 + 43617925*x^17 +
> >>> 92084825461*x^16 - 13577322967760*x^15 - 7694013534722665*x^14 +
> >>> 1430561593275815035*x^13 + 321534254513790999596*x^12 -
> >>> 7029914549841232012519
> >>> : 0*x^11 - 6894702144208513885815805*x^10 +
> >>> 1786517983436254067840917780*x^9 + 72426826805051978098685836211*x^8 -
> >>> 24338190557208310471662504670520*x^7 -
> >>> 255231848841911020332784180965840*x^6 + 17
> >>> : 2908549561723112381441893500998965*x^5 -
> >>> 1042438501414486010172621550211101919*x^4 -
> >>> 555813027721813935650430329326884907050*x^3 +
> >>> 6754721428610694790490649672796107843280*x^2 + 4708107071244139
> >>> : 68773034018937652067163520*x +
> >>> 3896560262532181966922924457358135376686480)
> >>> sage:
> >>> sage: Kf.=NumberField(f)
> >>> sage: Kg.=NumberField(g)
> >>> sage: flag, isos = Kf.is_isomorphic(Kg, isomorphism_maps=True); flag
> >>> True
> >>> sage: len(isos)
> >>> 2
> >>>
> >>> but
> >>>
> >>> sage: Kf.embeddings(Kg)
> >>> ---
> >>> PariError  Traceback (most recent call last)
> >>> (...)
> >>> PariError: inconsistent exact division t_INT , t_INT
> >>>
> >>>
> >>> as a result of
> >>>
> >>> sage: f.roots(Kg)
> >>>
> >>> raising the same error.  I suspect that the root-finding needs higher
> >>> precision that it

Re: [sage-devel] bug in interface to pari's nffactor

2018-09-14 Thread Bruno Grenet

I've also tested on Ubuntu with gcc. Actually, I run new tests: The bug 
appears between 8.4beta2 (where it's still ok) and 8.4beta3. I'll try to 
find the the origin of the bug.


Bruno

Le 14/09/2018 à 10:38, Dima Pasechnik a écrit :

It might be a platform dependent bug. I guess John is working on some
Ubunty machine, using gcc.

Please provide compiler details you're using, too...



On Fri, Sep 14, 2018 at 9:25 AM Bruno Grenet  wrote:

Which version of SageMath are you using? I am unable to reproduce the
bug neither on 8.3beta7 nor on 8.4beta2.

Bruno

Example with 8.4beta2:

sage: x = polygen(QQ)
sage: f = x^20 - 15*x^19 + 70989*x^18 - 1646113*x^17 + 3890074283*x^16 -
199035549796*x^15 + 203804256639644*x^14 - 10
: 657741285726487*x^13 + 9779630086245476401*x^12 -
457685358591718595073*x^11 + 211985887298317287648516*x^10 - 1
: 3621268697129972225420327*x^9 + 3065457104886066023133986949*x^8 -
28110542105571309419720191704*x^7 + 345396659
: 71867983088754678645580*x^6 -
1061445386217881235978009629856081*x^5 +
498395492968339432558541006017143039*x^4
: - 15789239186368833250097534490638459475*x^3 +
1774782276941552319212370439848636475557*x^2 + 446933009353599830
: 6027448264353195140536*x + 4277406750726325717327241436124994515881
:
sage: g = x^20 - 5*x^19 - 497395*x^18 + 43617925*x^17 + 92084825461*x^16
- 13577322967760*x^15 - 7694013534722665*x^14
:  + 1430561593275815035*x^13 + 321534254513790999596*x^12 -
70299145498412320125190*x^11 - 6894702144208513885815
: 805*x^10 + 1786517983436254067840917780*x^9 +
72426826805051978098685836211*x^8 - 243381905572083104716625046705
: 20*x^7 - 255231848841911020332784180965840*x^6 +
172908549561723112381441893500998965*x^5 - 10424385014144860101
: 72621550211101919*x^4 -
555813027721813935650430329326884907050*x^3 +
6754721428610694790490649672796107843280*x
: ^2 + 470810707124413968773034018937652067163520*x +
3896560262532181966922924457358135376686480
:
sage: Kf. = NumberField(f)
sage: Kg. = NumberField(g)
sage: embeddings = Kf.embeddings(Kg)
sage: len(embeddings)
2


Le 13/09/2018 à 16:16, John Cremona a écrit :

I have two polynomials of degree 20 defining the same number field (I
obtained the second from the first using pari's polredbest()
routine).  I am able to use is_isomorphic() to find isomorphisms
between them (there are 2) but embeddings() raises an error since
roots() does:

sage: x = polygen(QQ)
sage: f = (x^20 - 15*x^19 + 70989*x^18 - 1646113*x^17 +
3890074283*x^16 - 199035549796*x^15 + 203804256639644*x^14 -
10657741285726487*x^13 + 9779630086245476401*x^12 -
457685358591718595073*x^11 + 21
: 1985887298317287648516*x^10 - 13621268697129972225420327*x^9 +
3065457104886066023133986949*x^8 - 28110542105571309419720191704*x^7 +
34539665971867983088754678645580*x^6 - 106144538621788123597
: 8009629856081*x^5 + 498395492968339432558541006017143039*x^4 -
15789239186368833250097534490638459475*x^3 +
1774782276941552319212370439848636475557*x^2 +
446933009353599830602744826435319514053
: 6*x + 4277406750726325717327241436124994515881)
sage: g = (x^20 - 5*x^19 - 497395*x^18 + 43617925*x^17 +
92084825461*x^16 - 13577322967760*x^15 - 7694013534722665*x^14 +
1430561593275815035*x^13 + 321534254513790999596*x^12 -
7029914549841232012519
: 0*x^11 - 6894702144208513885815805*x^10 +
1786517983436254067840917780*x^9 + 72426826805051978098685836211*x^8 -
24338190557208310471662504670520*x^7 -
255231848841911020332784180965840*x^6 + 17
: 2908549561723112381441893500998965*x^5 -
1042438501414486010172621550211101919*x^4 -
555813027721813935650430329326884907050*x^3 +
6754721428610694790490649672796107843280*x^2 + 4708107071244139
: 68773034018937652067163520*x +
3896560262532181966922924457358135376686480)
sage:
sage: Kf.=NumberField(f)
sage: Kg.=NumberField(g)
sage: flag, isos = Kf.is_isomorphic(Kg, isomorphism_maps=True); flag
True
sage: len(isos)
2

but

sage: Kf.embeddings(Kg)
---
PariError  Traceback (most recent call last)
(...)
PariError: inconsistent exact division t_INT , t_INT


as a result of

sage: f.roots(Kg)

raising the same error.  I suspect that the root-finding needs higher
precision that it is using, but the fact that is_isomorphic() works
fine suggests that this can be dealt with.

The relevant code seems to be buried
in sage/rings/polynomial/polynomial_element.pyx around line 4300 (!).
I don't have tim right now to investigate further or even create a
trac ticket.

John
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Re: [sage-devel] bug in interface to pari's nffactor

2018-09-14 Thread Dima Pasechnik

It might be a platform dependent bug. I guess John is working on some
Ubunty machine, using gcc.

Please provide compiler details you're using, too...



On Fri, Sep 14, 2018 at 9:25 AM Bruno Grenet  wrote:
>
> Which version of SageMath are you using? I am unable to reproduce the
> bug neither on 8.3beta7 nor on 8.4beta2.
>
> Bruno
>
> Example with 8.4beta2:
>
> sage: x = polygen(QQ)
> sage: f = x^20 - 15*x^19 + 70989*x^18 - 1646113*x^17 + 3890074283*x^16 -
> 199035549796*x^15 + 203804256639644*x^14 - 10
> : 657741285726487*x^13 + 9779630086245476401*x^12 -
> 457685358591718595073*x^11 + 211985887298317287648516*x^10 - 1
> : 3621268697129972225420327*x^9 + 3065457104886066023133986949*x^8 -
> 28110542105571309419720191704*x^7 + 345396659
> : 71867983088754678645580*x^6 -
> 1061445386217881235978009629856081*x^5 +
> 498395492968339432558541006017143039*x^4
> : - 15789239186368833250097534490638459475*x^3 +
> 1774782276941552319212370439848636475557*x^2 + 446933009353599830
> : 6027448264353195140536*x + 4277406750726325717327241436124994515881
> :
> sage: g = x^20 - 5*x^19 - 497395*x^18 + 43617925*x^17 + 92084825461*x^16
> - 13577322967760*x^15 - 7694013534722665*x^14
> :  + 1430561593275815035*x^13 + 321534254513790999596*x^12 -
> 70299145498412320125190*x^11 - 6894702144208513885815
> : 805*x^10 + 1786517983436254067840917780*x^9 +
> 72426826805051978098685836211*x^8 - 243381905572083104716625046705
> : 20*x^7 - 255231848841911020332784180965840*x^6 +
> 172908549561723112381441893500998965*x^5 - 10424385014144860101
> : 72621550211101919*x^4 -
> 555813027721813935650430329326884907050*x^3 +
> 6754721428610694790490649672796107843280*x
> : ^2 + 470810707124413968773034018937652067163520*x +
> 3896560262532181966922924457358135376686480
> :
> sage: Kf. = NumberField(f)
> sage: Kg. = NumberField(g)
> sage: embeddings = Kf.embeddings(Kg)
> sage: len(embeddings)
> 2
>
>
> Le 13/09/2018 à 16:16, John Cremona a écrit :
> > I have two polynomials of degree 20 defining the same number field (I
> > obtained the second from the first using pari's polredbest()
> > routine).  I am able to use is_isomorphic() to find isomorphisms
> > between them (there are 2) but embeddings() raises an error since
> > roots() does:
> >
> > sage: x = polygen(QQ)
> > sage: f = (x^20 - 15*x^19 + 70989*x^18 - 1646113*x^17 +
> > 3890074283*x^16 - 199035549796*x^15 + 203804256639644*x^14 -
> > 10657741285726487*x^13 + 9779630086245476401*x^12 -
> > 457685358591718595073*x^11 + 21
> > : 1985887298317287648516*x^10 - 13621268697129972225420327*x^9 +
> > 3065457104886066023133986949*x^8 - 28110542105571309419720191704*x^7 +
> > 34539665971867983088754678645580*x^6 - 106144538621788123597
> > : 8009629856081*x^5 + 498395492968339432558541006017143039*x^4 -
> > 15789239186368833250097534490638459475*x^3 +
> > 1774782276941552319212370439848636475557*x^2 +
> > 446933009353599830602744826435319514053
> > : 6*x + 4277406750726325717327241436124994515881)
> > sage: g = (x^20 - 5*x^19 - 497395*x^18 + 43617925*x^17 +
> > 92084825461*x^16 - 13577322967760*x^15 - 7694013534722665*x^14 +
> > 1430561593275815035*x^13 + 321534254513790999596*x^12 -
> > 7029914549841232012519
> > : 0*x^11 - 6894702144208513885815805*x^10 +
> > 1786517983436254067840917780*x^9 + 72426826805051978098685836211*x^8 -
> > 24338190557208310471662504670520*x^7 -
> > 255231848841911020332784180965840*x^6 + 17
> > : 2908549561723112381441893500998965*x^5 -
> > 1042438501414486010172621550211101919*x^4 -
> > 555813027721813935650430329326884907050*x^3 +
> > 6754721428610694790490649672796107843280*x^2 + 4708107071244139
> > : 68773034018937652067163520*x +
> > 3896560262532181966922924457358135376686480)
> > sage:
> > sage: Kf.=NumberField(f)
> > sage: Kg.=NumberField(g)
> > sage: flag, isos = Kf.is_isomorphic(Kg, isomorphism_maps=True); flag
> > True
> > sage: len(isos)
> > 2
> >
> > but
> >
> > sage: Kf.embeddings(Kg)
> > ---
> > PariError  Traceback (most recent call last)
> > (...)
> > PariError: inconsistent exact division t_INT , t_INT
> >
> >
> > as a result of
> >
> > sage: f.roots(Kg)
> >
> > raising the same error.  I suspect that the root-finding needs higher
> > precision that it is using, but the fact that is_isomorphic() works
> > fine suggests that this can be dealt with.
> >
> > The relevant code seems to be buried
> > in sage/rings/polynomial/polynomial_element.pyx around line 4300 (!).
> > I don't have tim right now to investigate further or even create a
> > trac ticket.
> >
> > John
> > --
> > You received this message because you are subscribed to the Google
> > Groups "sage-devel" group.
> > To unsubscribe from this group and stop receiving emails from it, send
> > an email to sage-devel+unsubscr...@googlegroups.com
> > .
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Re: [sage-devel] bug in interface to pari's nffactor

2018-09-14 Thread Bruno Grenet

Which version of SageMath are you using? I am unable to reproduce the 
bug neither on 8.3beta7 nor on 8.4beta2.


Bruno

Example with 8.4beta2:

sage: x = polygen(QQ)
sage: f = x^20 - 15*x^19 + 70989*x^18 - 1646113*x^17 + 3890074283*x^16 - 
199035549796*x^15 + 203804256639644*x^14 - 10
: 657741285726487*x^13 + 9779630086245476401*x^12 - 
457685358591718595073*x^11 + 211985887298317287648516*x^10 - 1
: 3621268697129972225420327*x^9 + 3065457104886066023133986949*x^8 - 
28110542105571309419720191704*x^7 + 345396659
: 71867983088754678645580*x^6 - 
1061445386217881235978009629856081*x^5 + 
498395492968339432558541006017143039*x^4
: - 15789239186368833250097534490638459475*x^3 + 
1774782276941552319212370439848636475557*x^2 + 446933009353599830

: 6027448264353195140536*x + 4277406750726325717327241436124994515881
:
sage: g = x^20 - 5*x^19 - 497395*x^18 + 43617925*x^17 + 92084825461*x^16 
- 13577322967760*x^15 - 7694013534722665*x^14
:  + 1430561593275815035*x^13 + 321534254513790999596*x^12 - 
70299145498412320125190*x^11 - 6894702144208513885815
: 805*x^10 + 1786517983436254067840917780*x^9 + 
72426826805051978098685836211*x^8 - 243381905572083104716625046705
: 20*x^7 - 255231848841911020332784180965840*x^6 + 
172908549561723112381441893500998965*x^5 - 10424385014144860101
: 72621550211101919*x^4 - 
555813027721813935650430329326884907050*x^3 + 
6754721428610694790490649672796107843280*x
: ^2 + 470810707124413968773034018937652067163520*x + 
3896560262532181966922924457358135376686480

:
sage: Kf. = NumberField(f)
sage: Kg. = NumberField(g)
sage: embeddings = Kf.embeddings(Kg)
sage: len(embeddings)
2


Le 13/09/2018 à 16:16, John Cremona a écrit :
I have two polynomials of degree 20 defining the same number field (I 
obtained the second from the first using pari's polredbest() 
routine).  I am able to use is_isomorphic() to find isomorphisms 
between them (there are 2) but embeddings() raises an error since 
roots() does:


sage: x = polygen(QQ)
sage: f = (x^20 - 15*x^19 + 70989*x^18 - 1646113*x^17 + 
3890074283*x^16 - 199035549796*x^15 + 203804256639644*x^14 - 
10657741285726487*x^13 + 9779630086245476401*x^12 - 
457685358591718595073*x^11 + 21
: 1985887298317287648516*x^10 - 13621268697129972225420327*x^9 + 
3065457104886066023133986949*x^8 - 28110542105571309419720191704*x^7 + 
34539665971867983088754678645580*x^6 - 106144538621788123597
: 8009629856081*x^5 + 498395492968339432558541006017143039*x^4 - 
15789239186368833250097534490638459475*x^3 + 
1774782276941552319212370439848636475557*x^2 + 
446933009353599830602744826435319514053

: 6*x + 4277406750726325717327241436124994515881)
sage: g = (x^20 - 5*x^19 - 497395*x^18 + 43617925*x^17 + 
92084825461*x^16 - 13577322967760*x^15 - 7694013534722665*x^14 + 
1430561593275815035*x^13 + 321534254513790999596*x^12 - 
7029914549841232012519
: 0*x^11 - 6894702144208513885815805*x^10 + 
1786517983436254067840917780*x^9 + 72426826805051978098685836211*x^8 - 
24338190557208310471662504670520*x^7 - 
255231848841911020332784180965840*x^6 + 17
: 2908549561723112381441893500998965*x^5 - 
1042438501414486010172621550211101919*x^4 - 
555813027721813935650430329326884907050*x^3 + 
6754721428610694790490649672796107843280*x^2 + 4708107071244139
: 68773034018937652067163520*x + 
3896560262532181966922924457358135376686480)

sage:
sage: Kf.=NumberField(f)
sage: Kg.=NumberField(g)
sage: flag, isos = Kf.is_isomorphic(Kg, isomorphism_maps=True); flag
True
sage: len(isos)
2

but

sage: Kf.embeddings(Kg)
---
PariError  Traceback (most recent call last)
(...)
PariError: inconsistent exact division t_INT , t_INT


as a result of

sage: f.roots(Kg)

raising the same error.  I suspect that the root-finding needs higher 
precision that it is using, but the fact that is_isomorphic() works 
fine suggests that this can be dealt with.


The relevant code seems to be buried 
in sage/rings/polynomial/polynomial_element.pyx around line 4300 (!).  
I don't have tim right now to investigate further or even create a 
trac ticket.


John
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[sage-devel] Re: Buggy doctest in sage.modules.free_module.EchelonMatrixKey

2018-09-14 Thread Simon Brandhorst



On Thursday, September 13, 2018 at 2:42:44 PM UTC+2, Erik Bray wrote:
>
> However, reading the documentation for EchelonMatrixKey and 
> echelon_matrix_richcmp gives me the impression that this nonsensical 
> comparison isn't really the right behavior in the first place, but I'm 
> not sure.  Any experts on this code want to weight in? 
>

This ordering is the historical order on modules. It is still used in the 
modular forms code to make the output of some functions deterministic.
The default ordering was changed in https://trac.sagemath.org/ticket/23978 
to inclusion.

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Re: [sage-devel] bug in interface to pari's nffactor

Re: [sage-devel] bug in interface to pari's nffactor

Re: [sage-devel] bug in interface to pari's nffactor

Re: [sage-devel] bug in interface to pari's nffactor

[sage-devel] Re: Buggy doctest in sage.modules.free_module.EchelonMatrixKey

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