[sage-support] Re: How should I determine if two strongly regular graphs are isomorphic?

[Dima Pasechnik]

Do I get it right that each graph of yours can be constructed from a 
projective 2-weight code over GF(2)?

Sage has a small database of such codes, so one can add your graphs there 
in this form.
See strongly_regular_from_two_intersection_set 
and strongly_regular_from_two_weight_code
in sage.graphs.strongly_regular_db



On Wednesday, December 14, 2016 at 2:49:48 AM UTC, Paul Leopardi wrote:
>
> Hi again Dima,
> For the record, see below.
>
> On Wednesday, 24 August 2016 00:46:06 UTC+10, Dima Pasechnik wrote:
>>
>> Hi,
>>
>> I think the best way to fix your issue is to fix 
>> https://trac.sagemath.org/ticket/21313
>> This will allow is_isomorphic to use bliss or nauty.
>> (In fact, IIRC checking for isomorphism is in practice a bit faster than 
>> canonical labelling).
>>
>> Also, do I get it right that you have a new "generic" construction of 
>> strongly regular graphs?
>> As you know, we are collecting them - would you be interested in adding 
>> it into sage/graphs/generators/ ?
>>
>> Dima
>>
>>
> How do I add to sage/graphs/generators , based o what I have now, as 
> described below?
>
> I have been developing Sage and Python code for use in my exploration of 
> bent functions and their strongly regular Cayley graphs as described in my 
> recent (today) talk;
> Classifying bent functions by their Cayley graphs, using Sage 
> ,
>  
> 40 ACCMCC, 2016.
> The code (and manuscript) repository is at  
> https://github.com/penguian/Boolean-Cayley-graphs
> There is also a public SageMathCloud directory at 
>
> https://cloud.sagemath.com/projects/80f4c9e7-8a37-4f59-82e7-aa179ec0b652/files/Boolean-Cayley-graphs/
> with extra SageMathCloud worksheets.
>
> I am in the process of updating the code and especially the comments to 
> conform to SageMath expectations, and porting some of the Sage code to 
> Python, where sensible, but some will remain as Sage code.
>
>

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Re: [sage-support] integral points on ellipitc curves

[drazioti]

Thank you both for the answers,

I found another problematic example

sage:E1=EllipticCurve([0,0,0,37,18]);E1;S=E1.integral_points();S;
Elliptic Curve defined by y^2 = x^3 + 37*x + 18 
over Rational Field 
[(2 : 10 : 1), (126 : 1416 : 1)]



and 

R = E1(64039202,512470496030);M=E1(2,10 );3*M==R
True

Both examples are from the paper 
of Don Zagier: Large integral points on Elliptic curves 


Also, I tried the previous examples in the online calculator of magma and 
seems that magma works fine.
  magma: E := EllipticCurve([0,0,0,37,18]);
 IntegralPoints(E);
[ (2 : 10 : 1), (126 : 1416 : 1), (64039202 : 512470496030 : 1) ]
[ <(2 : 10 : 1), 1>, <(126 : 1416 : 1), 1>, 
<(64039202 : 512470496030 : 1), 1> ]



I use this function a lot and  
I think many people (heavily) use this function
for their research. I was not aware of the problems of this function :(

I am wondering if this bug affects other functions concerning 
elliptic curves?

Thanks again for the answers
Costas. 





On Wednesday, December 14, 2016 at 10:25:25 PM UTC+2, Nils Bruin wrote:
>
> On Wednesday, December 14, 2016 at 12:09:36 PM UTC-8, John Cremona wrote:
>>
>>
>> Thanks for the bug report.  As Nils pointed out there are known bugs 
>> in the integral point code which cause solutions to be missed.
>
>
> Just to make clear: I wasn't taking a jibe at sage/or John on this, and I 
> wasn't previously aware there are bugs in the integral points code in Sage. 
> I was just observing that in the past 20 years, any computer algebra 
> package that implements integral point finding on elliptic curves has had 
> significant errors (of the type reported here). Apparently it's something 
> that is particularly hard to get reliably correct.
>

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Re: [sage-support] integral points on ellipitc curves

[Nils Bruin]

On Wednesday, December 14, 2016 at 12:09:36 PM UTC-8, John Cremona wrote:
>
>
> Thanks for the bug report.  As Nils pointed out there are known bugs 
> in the integral point code which cause solutions to be missed.


Just to make clear: I wasn't taking a jibe at sage/or John on this, and I 
wasn't previously aware there are bugs in the integral points code in Sage. 
I was just observing that in the past 20 years, any computer algebra 
package that implements integral point finding on elliptic curves has had 
significant errors (of the type reported here). Apparently it's something 
that is particularly hard to get reliably correct.

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[sage-support] Re: Sage crash report 7.0

[Dima Pasechnik]

On Wednesday, December 14, 2016 at 7:31:30 PM UTC, Laurent Bakri wrote:
>
>
> Hmm.. this is getting hard to follow the thread... 
> Yes there is a reason I can't upgrade  (with the last gcc there is an  
> error on flint described here "-r and -pie may not be used together" 
> 
> while compiling from source (or upgrading )  and the binary install from 
> scratch  does not work either (but i forgot the error) 
> Althought there was a patch suggested to compile the last version in this 
> google group  somewhere. hould I focus on that on your opinion ? 
>

I think the latest Sage beta (7.5.beta6) already includes this fix.
Get it here https://github.com/sagemath/sage/tree/develop
and build from source.

 

> Thanks a lot 
>
>   
> 
> Le mercredi 14 décembre 2016 14:28:09 UTC+1, Laurent Bakri a écrit :
>>
>>
>>
>> Hi all, 
>> I am using sage  on Debian (sid)
>> Sagemath 7.0 was working fine until an upgrade of python  to version 3 
>> Then it stop working with an syntax error due to python 3  
>> So I (re)lnked pyhton to python 2.7 but now it crashes for a reason I 
>> cannot determine 
>> here is the crash report 
>> Thanks in advance,
>>
>>

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Re: [sage-support] integral points on ellipitc curves

[John Cremona]

Dear Costas,

Thanks for the bug report.  As Nils pointed out there are known bugs
in the integral point code which cause solutions to be missed.  A lot
of work has been spent on improving this, in part by me, and the main
reason the fixes have not yet been approved and merged is that I still
had more work to do on it and it got forgotten.

This example is odd though.  The rank is 3 (as you can see from
E1.gens()) and when you run E1.integral_points(verbose=True) you can
see that it does correctly compute  a bound of 3 on the coefficients
of the integral points as a Z-linear combination of the generators.
(There is no torsion).  This may be a precision issue since the final
search does use real arithmetic, in the (non-global) function
integral_points_with_bounded_mw_coefficients().  There is a comment in
there which says

# Otherwise it is very very much faster to first compute
# the linear combinations over RR, and only compute them as
# rational points if they are approximately integral.

# Note: making eps larger here will dramatically increase
# the running time.  If evidence arises that integral
# points are being missed, it would be better to increase
# the real precision than to increase eps.

and I think you have just found such evidence.

John Cremona

On 14 December 2016 at 17:07,   wrote:
>
> Hi all,
>
> I came across the following example...
>
> sage: E1=EllipticCurve([0,0,0,49,-64]);E1;S=E1.integral_points();S;
>
> Elliptic Curve defined by y^2 = x^3 + 49*x - 64 over Rational Field
> [(4 : 14 : 1), (464 : 9996 : 1)]
>
> but the following integer point Q belongs also to the curve
>
> sage:Q=E1(482042404,10583464697386);Q
>
>
> (482042404 : 10583464697386 : 1)
>
> further, Q=3*M.
>
>
> Any idea why sage did not provide the point Q?
> I used  sage version 6.9.
>
> Thank you
>
> Costas
>
> --
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[sage-support] Re: Sage crash report 7.0

[Laurent Bakri]

Hmm.. this is getting hard to follow the thread... 
Yes there is a reason I can't upgrade  (with the last gcc there is an  
error on flint described here "-r and -pie may not be used together" 

while compiling from source (or upgrading )  and the binary install from 
scratch  does not work either (but i forgot the error) 
Althought there was a patch suggested to compile the last version in this 
google group  somewhere. hould I focus on that on your opinion ? 
Thanks a lot 

  

Le mercredi 14 décembre 2016 14:28:09 UTC+1, Laurent Bakri a écrit :
>
>
>
> Hi all, 
> I am using sage  on Debian (sid)
> Sagemath 7.0 was working fine until an upgrade of python  to version 3 
> Then it stop working with an syntax error due to python 3  
> So I (re)lnked pyhton to python 2.7 but now it crashes for a reason I 
> cannot determine 
> here is the crash report 
> Thanks in advance,
>
>

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[sage-support] Re: integral points on ellipitc curves

[Nils Bruin]

On Wednesday, December 14, 2016 at 9:07:50 AM UTC-8, draz...@gmail.com 
wrote:
>
>
> Any idea why sage did not provide the point Q?
> I used  sage version 6.9.
>

It's sage's own code. Sage is definitely following a venerable tradition of 
getting integer points on elliptic curves wrong. 

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[sage-support] integral points on ellipitc curves

[drazioti]

Hi all,

I came across the following example...

sage: E1=EllipticCurve([0,0,0,49,-64]);E1;S=E1.integral_points();S;

Elliptic Curve defined by y^2 = x^3 + 49*x - 64 over Rational Field
[(4 : 14 : 1), (464 : 9996 : 1)]

but the following integer point Q belongs also to the curve

sage:Q=E1(482042404,10583464697386);Q


(482042404 : 10583464697386 : 1)

further, Q=3*M.


Any idea why sage did not provide the point Q?
I used  sage version 6.9.

Thank you

Costas

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Re: [sage-support] Re: Sage crash report 7.0

[Dima Pasechnik]

On Wednesday, December 14, 2016 at 3:44:19 PM UTC, NITIN DARKUNDE wrote:
>
> Hello, I have some old version of sage installed two years ago on my 
> laptop. Also some worksheets are saved on it. How to upgrade it to latest 
> 7.4 version? Whether old saved worksheets will remain saved? or get deleted?
>

You can always download the worksheets into files and save them to some 
reasonable place. (With an open worksheet such an option is in File menu, I 
think).
Normally it's a file with .sws extension.
And you can do the opposite, load a worksheet from a file.

I'd recommend to install a new version of Sage, not to upgrade the existing 
one (an upgrade from such an old version won't be possible anyway).
Then you can load your worksheets into the new version.




  

>
> On Dec 14, 2016 9:08 PM, "Dima Pasechnik" > 
> wrote:
>
> Is there any reason you cannot upgrade to a more recent version? The 
> current stable version is 7.4.
>
>
> On Wednesday, December 14, 2016 at 1:28:09 PM UTC, Laurent Bakri wrote:
>>
>>
>>
>> Hi all, 
>> I am using sage  on Debian (sid)
>> Sagemath 7.0 was working fine until an upgrade of python  to version 3 
>> Then it stop working with an syntax error due to python 3  
>> So I (re)lnked pyhton to python 2.7 but now it crashes for a reason I 
>> cannot determine 
>> here is the crash report 
>> Thanks in advance,
>>
>> -- 
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>
>
>

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Re: [sage-support] Re: Sage crash report 7.0

[NITIN DARKUNDE]

Hello, I have some old version of sage installed two years ago on my
laptop. Also some worksheets are saved on it. How to upgrade it to latest
7.4 version? Whether old saved worksheets will remain saved? or get deleted?

On Dec 14, 2016 9:08 PM, "Dima Pasechnik"  wrote:

Is there any reason you cannot upgrade to a more recent version? The
current stable version is 7.4.


On Wednesday, December 14, 2016 at 1:28:09 PM UTC, Laurent Bakri wrote:
>
>
>
> Hi all,
> I am using sage  on Debian (sid)
> Sagemath 7.0 was working fine until an upgrade of python  to version 3
> Then it stop working with an syntax error due to python 3
> So I (re)lnked pyhton to python 2.7 but now it crashes for a reason I
> cannot determine
> here is the crash report
> Thanks in advance,
>
> --
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[sage-support] Re: Sage crash report 7.0

[Dima Pasechnik]

Is there any reason you cannot upgrade to a more recent version? The 
current stable version is 7.4.

On Wednesday, December 14, 2016 at 1:28:09 PM UTC, Laurent Bakri wrote:
>
>
>
> Hi all, 
> I am using sage  on Debian (sid)
> Sagemath 7.0 was working fine until an upgrade of python  to version 3 
> Then it stop working with an syntax error due to python 3  
> So I (re)lnked pyhton to python 2.7 but now it crashes for a reason I 
> cannot determine 
> here is the crash report 
> Thanks in advance,
>
>

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[sage-support] Sage crash report 7.0

[Laurent Bakri]

Hi all, 
I am using sage  on Debian (sid)
Sagemath 7.0 was working fine until an upgrade of python  to version 3 
Then it stop working with an syntax error due to python 3  
So I (re)lnked pyhton to python 2.7 but now it crashes for a reason I 
cannot determine 
here is the crash report 
Thanks in advance,

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***

IPython post-mortem report

{'commit_hash': u'1961f94',
 'commit_source': 'installation',
 'default_encoding': 'UTF-8',
 'ipython_path': 
'/home/laurent/sage-7.0/local/lib/python2.7/site-packages/IPython',
 'ipython_version': '4.0.0',
 'os_name': 'posix',
 'platform': 'Linux-4.8.0-2-amd64-x86_64-with-debian-stretch-sid',
 'sys_executable': '/home/laurent/sage-7.0/local/bin/python',
 'sys_platform': 'linux2',
 'sys_version': '2.7.13rc1 (default, Dec  4 2016, 14:12:39) \n[GCC 6.2.1 
20161124]'}

***



***

Crash traceback:

---
---
TypeError Python 2.7.13rc1: /home/laurent/sage-7.0/local/bin/python
   Wed Dec 14 13:08:03 2016
A problem occurred executing Python code.  Here is the sequence of function
calls leading up to the error, with the most recent (innermost) call last.
/home/laurent/sage-7.0/src/bin/sage-ipython in ()
  1 #!/usr/bin/env python
  2 # -*- coding: utf-8 -*-
  3 """
  4 Sage IPython startup script.
  5 """
  6 
  7 # Install extra readline commands before IPython initialization
  8 from sage.repl.readline_extra_commands import *
  9 
 10 from sage.repl.interpreter import SageTerminalApp
 11 
 12 app = SageTerminalApp.instance()
---> 13 app.initialize()
global app.initialize = >
 14 app.start()

 in initialize(self=, argv=None)

/home/laurent/sage-7.0/local/lib/python2.7/site-packages/traitlets/config/application.pyc
 in catch_config_error(method=, 
app=, *args=(None,), **kwargs={})
 60 
 61 
#-
 62 # Application class
 63 
#-
 64 
 65 @decorator
 66 def catch_config_error(method, app, *args, **kwargs):
 67 """Method decorator for catching invalid config 
(Trait/ArgumentErrors) during init.
 68 
 69 On a TraitError (generally caused by bad config), this will print 
the trait's
 70 message, and exit the app.
 71 
 72 For use on init methods, to prevent invoking excepthook on invalid 
input.
 73 """
 74 try:
---> 75 return method(app, *args, **kwargs)
method = 
app = 
args = (None,)
kwargs = {}
 76 except (TraitError, ArgumentError) as e:
 77 app.print_help()
 78 app.log.fatal("Bad config encountered during initialization:")
 79 app.log.fatal(str(e))
 80 app.log.debug("Config at the time: %s", app.config)
 81 app.exit(1)
 82 
 83 
 84 class ApplicationError(Exception):
 85 pass
 86 
 87 class LevelFormatter(logging.Formatter):
 88 """Formatter with additional `highlevel` record
 89 
 90 This field is empty if log level is less than highlevel_limit,

/home/laurent/sage-7.0/local/lib/python2.7/site-packages/IPython/terminal/ipapp.pyc
 in initialize(self=, argv=None)
299 
300 return super(TerminalIPythonApp, self).parse_command_line(argv)
301 
302 @catch_config_error
303 def initialize(self, argv=None):
304 """Do actions after construct, but before starting the app."""
305 super(TerminalIPythonApp, self).initialize(argv)
306 if self.subapp is not None:
307 # don't bother initializing further, starting subapp
308 return
309 # print self.extra_args
310 if self.extra_args and not self.something_to_run:
311 self.file_to_run = self.extra_args[0]
312 self.init_path()
313 # create the shell
--> 314 self.init_shell()
self.init_shell = >
315 # and draw the banner
316 self.init_banner()
317 # Now a vari