[sage-devel] Re: bug in matrix solve over inexact coefficients?

[Dave Morris]

This is the expected behavior after trac #12406 
. The OUTPUT section of the 
docstring of solve_right says "... If the system is not square or does not 
have full rank, then a solution is attempted via other means. For example, 
over "RDF" or "CDF" a least-squares solution is returned..."

This makes sense, since testing for the existence of a solution over 
inexact rings is problematic, but I do think it would be better if the 
method could have some some reasonable test available, even if it is not 
the default.

On Thursday, May 21, 2020 at 6:44:09 PM UTC-6, AlexGhitza wrote:
>
> Hi,
>
> I'm observing the following with version 9.1 (but not with 9.0 where the 
> behavior is correct):
>
> sage: m = matrix(SR, [0])
> sage: b = vector([1])
> sage: m.solve_right(b)
> (0)
>
> This should of course raise
>
> ValueError: matrix equation has no solutions
>
>
> It seems to be specific to inexact coefficients (the same problem occurs 
> for RR and CC, but not for QQ).
>
>
> Best,
> Alex
>

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[sage-devel] bug in matrix solve over inexact coefficients?

[AlexGhitza]

Hi,

I'm observing the following with version 9.1 (but not with 9.0 where the 
behavior is correct):

sage: m = matrix(SR, [0])
sage: b = vector([1])
sage: m.solve_right(b)
(0)

This should of course raise

ValueError: matrix equation has no solutions


It seems to be specific to inexact coefficients (the same problem occurs 
for RR and CC, but not for QQ).


Best,
Alex

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Re: [sage-devel] Pre-Announcement: Global Virtual SageDays 109 - May 28, 2020 (all timezones)

[Matthias Koeppe]

On Thursday, May 21, 2020 at 1:04:07 PM UTC-7, François Bissey wrote:
>
> Hum. May 21, 19:30GMT = May 22 7:30 NZ time I was in the middle of 
> preparing breakfast 
> for the kids and we should go to school shortly. 
> Needless to say I won’t participate at 7:30am on a Saturday morning. 
>
>
Please feel free to suggest another meeting time.

 

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Re: [sage-devel] Pre-Announcement: Global Virtual SageDays 109 - May 28, 2020 (all timezones)

[François Bissey]

Indeed! I am part of HPCCF (HPC certification forum) and at the beginning of 
the week
we had some kind of assembly. In two parts.
UK->Americas on Monday [would have turned out as 2am Tuesday for me]
UK->NZ on Wednesday [it was still 8pm to 10pm for NZ-ers like me]

> On 22/05/2020, at 8:13 AM, Dima Pasechnik  wrote:
> 
> well, yes, it's a well-known problem, that EU+US+NZ online meetings
> are basically impossible to schedule :-(
> 
> 

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Re: [sage-devel] Pre-Announcement: Global Virtual SageDays 109 - May 28, 2020 (all timezones)

[Dima Pasechnik]

On Thu, May 21, 2020 at 9:04 PM François Bissey  wrote:
>
> Hum. May 21, 19:30GMT = May 22 7:30 NZ time I was in the middle of preparing 
> breakfast
> for the kids and we should go to school shortly.
> Needless to say I won’t participate at 7:30am on a Saturday morning.

well, yes, it's a well-known problem, that EU+US+NZ online meetings
are basically impossible to schedule :-(

>
> François
>
> > On 22/05/2020, at 7:57 AM, Matthias Koeppe  wrote:
> >
> > On Thursday, May 21, 2020 at 10:04:26 AM UTC-7, Matthias Koeppe wrote:
> > The Global Virtual SageDays 109 will be held on May 28, 2020 (all 
> > timezones).
> >
> > I have updated https://wiki.sagemath.org/days109 and created the stream 
> > #sd109 on https://zulip.sagemath.org/
> >
> >
> > People interested in helping with the organization, or contributing 
> > presentations, please respond here or on zulip.
> >
> > For synchronous communication, let's meet TODAY, May 21, 19:30 GMT = 21:30 
> > CEST = 15:30 EDT = 12:30 PDT on zulip.
> >
> >
> > Next organization meeting = Friday May 22, 19:30 GMT = 21:30 CEST = 15:30 
> > EDT = 12:30 PDT on zulip.
> >
> >
> >
> > --
> > 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.
> > To view this discussion on the web visit 
> > https://groups.google.com/d/msgid/sage-devel/0be3d70e-2ea2-4c80-ae19-4a62a23f59ab%40googlegroups.com.
>
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Re: [sage-devel] Pre-Announcement: Global Virtual SageDays 109 - May 28, 2020 (all timezones)

[François Bissey]

Hum. May 21, 19:30GMT = May 22 7:30 NZ time I was in the middle of preparing 
breakfast
for the kids and we should go to school shortly.
Needless to say I won’t participate at 7:30am on a Saturday morning.

François

> On 22/05/2020, at 7:57 AM, Matthias Koeppe  wrote:
> 
> On Thursday, May 21, 2020 at 10:04:26 AM UTC-7, Matthias Koeppe wrote:
> The Global Virtual SageDays 109 will be held on May 28, 2020 (all timezones).
> 
> I have updated https://wiki.sagemath.org/days109 and created the stream 
> #sd109 on https://zulip.sagemath.org/
> 
> 
> People interested in helping with the organization, or contributing 
> presentations, please respond here or on zulip.
> 
> For synchronous communication, let's meet TODAY, May 21, 19:30 GMT = 21:30 
> CEST = 15:30 EDT = 12:30 PDT on zulip.
> 
> 
> Next organization meeting = Friday May 22, 19:30 GMT = 21:30 CEST = 15:30 EDT 
> = 12:30 PDT on zulip.
> 
>  
> 
> -- 
> You received this message because you are subscribed to the Google Groups 
> "sage-devel" group.
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> https://groups.google.com/d/msgid/sage-devel/0be3d70e-2ea2-4c80-ae19-4a62a23f59ab%40googlegroups.com.

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[sage-devel] Re: Pre-Announcement: Global Virtual SageDays 109 - May 28, 2020 (all timezones)

[Matthias Koeppe]

On Thursday, May 21, 2020 at 10:04:26 AM UTC-7, Matthias Koeppe wrote:
>
> The Global Virtual SageDays 109 will be held on May 28, 2020 (all 
> timezones).
>
> I have updated https://wiki.sagemath.org/days109 and created the stream 
> #sd109 on https://zulip.sagemath.org/
>
>
> People interested in helping with the organization, or contributing 
> presentations, please respond here or on zulip.
>
> For synchronous communication, let's meet TODAY, May 21, 19:30 GMT = 21:30 
> CEST = 15:30 EDT = 12:30 PDT on zulip.
>
>
Next organization meeting = Friday May 22, 19:30 GMT = 21:30 CEST = 15:30 
EDT = 12:30 PDT on zulip.

 

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[sage-devel] Pre-Announcement: Global Virtual SageDays 109 - May 28, 2020 (all timezones)

[Matthias Koeppe]

The Global Virtual SageDays 109 will be held on May 28, 2020 (all 
timezones).

I have updated https://wiki.sagemath.org/days109 and created the stream 
#sd109 on https://zulip.sagemath.org/


People interested in helping with the organization, or contributing 
presentations, please respond here or on zulip.

For synchronous communication, let's meet TODAY, May 21, 19:30 GMT = 21:30 
CEST = 15:30 EDT = 12:30 PDT on zulip.



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Re: [sage-devel] Flint-2.6.0 alpha release (testing requested)

['Bill Hart' via sage-devel]

I will tag the first release candidate, as already mentioned. I don't like 
the repo being filled up with tags, so if we are going to use them I'll be 
keeping them to a minimum. Having tags permanently in there for something 
that served a purpose for one week only seems horrible to me.

Having said that, I should clean up more dead branches in my repo.

On Thursday, 21 May 2020 13:30:49 UTC+2, Julien Puydt wrote:
>
> Le jeudi 14 mai 2020 à 18:51 +0200, 'Bill Hart' via sage-devel a 
> écrit : 
>
> > The (latest) commit c6319d1d36248f2fc699e833ab2f6fa70d21e906 in the 
> > official Flint repository [1] is flint-2.6.0-alpha1. 
>
> You could tag it : that would be clearer. 
>
> Something like "git tag 2.6.0-alpha1" then "git push --tags" is enough. 
> That way the repository will document which tag is that alpha1, and 
> github will make tarballs automatically. 
>
> Cheers, 
>
> JP 
>
>

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[sage-devel] Re: [mpir-devel] Re: Flint-2.6.0 alpha release (testing requested)

['Bill Hart' via sage-devel]

Thanks Dima!

On Thu, 21 May 2020 at 12:31, Dima Pasechnik  wrote:
>
> On Wed, May 20, 2020 at 5:40 PM 'Bill Hart' via mpir-devel
>  wrote:
> >
> > Hi again,
> >
> > Commit a960857c7d8e5ea7c4d4c2958e38ec52778d85d9  of the Flint
> > repository [1] is now flint-2.6.0-alpha2
> >
> > This is the last chance for developers working on related projects to
> > see if Flint works as expected for them, before we start asking end
> > users/distributions to start testing.
> >
> > We have made many modifications since alpha1, including:
> >
> > * removing all known memory leaks
> > * fixing a bug in the integer gcd (leak, inefficiency, very slim
> > chance of wrong answer)
> > * properly supporting GMP-6.2
> > * making matrices with zero rows/columns more robust
> > * many other less important fixes (35 commits total)
> > * fixing a bug/crash in the _f functions in the fmpz_mod_poly module
> >
>
> OK, so now it passes on everything I tried it on (most exotic:
> clang-8.0.1 on OpenBSD, with NTL enabled)
> Will now try to test it with Sage (https://trac.sagemath.org/ticket/29719)
>
>
> > We don't foresee the need for any further alpha releases, (assuming no
> > major issues are found). The next release will likely either be a beta
> > or release candidate. Please note the only important things that
> > remain to be done as far as we know are documentation/paperwork
> > related [2].
> >
> > Please report bugs on our GitHub issue tracker. Successful builds can
> > be reported here.
> >
> > Best Wishes,
> >
> > The Flint Development Team
> >
> > P.S. thanks to the Flint package maintainer in the Fedora project who
> > did early reporting/patching of many issues and to the numerous people
> > who gave feedback on the first alpha! Many more acknowledgements to
> > come in the release announcement!
> >
> > [1] https://github.com/wbhart/flint2
> > [2] https://github.com/wbhart/flint2/milestone/2
> >
> > --
> > You received this message because you are subscribed to the Google Groups 
> > "mpir-devel" group.
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>
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[sage-devel] Could someone point me to the code that supports math on symbolic equations?

[Jonathan]

Dear All,

I have a use case where I need something lighter weight than the whole of 
Sagemath. I think SymPy + the ability to handle math on symbolic equations 
as Sagemath does it might be enough. Thus I wanted to see if I could 
extract from Sagemath the code supporting math on symbolic expressions and 
overlay that on SymPy or at least use that as a template. Can somebody 
please point me to the place to start looking in the codebase?

To make sure people understand what I am interested in, here is a simple 
example of the ability I would like to extract:
>>>eq1 = p*V==n*R*T
>>>eq1
p*V=n*R*T
>>>eq2=eq1/V
>>>eq2
p=n*R*T/V

Thanks,
Jonathan

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Re: [sage-devel] Flint-2.6.0 alpha release (testing requested)

[Julien Puydt]

Le jeudi 14 mai 2020 à 18:51 +0200, 'Bill Hart' via sage-devel a
écrit :

> The (latest) commit c6319d1d36248f2fc699e833ab2f6fa70d21e906 in the
> official Flint repository [1] is flint-2.6.0-alpha1.

You could tag it : that would be clearer.

Something like "git tag 2.6.0-alpha1" then "git push --tags" is enough.
That way the repository will document which tag is that alpha1, and
github will make tarballs automatically.

Cheers,

JP

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[sage-devel] Re: [mpir-devel] Re: Flint-2.6.0 alpha release (testing requested)

[Dima Pasechnik]

On Wed, May 20, 2020 at 5:40 PM 'Bill Hart' via mpir-devel
 wrote:
>
> Hi again,
>
> Commit a960857c7d8e5ea7c4d4c2958e38ec52778d85d9  of the Flint
> repository [1] is now flint-2.6.0-alpha2
>
> This is the last chance for developers working on related projects to
> see if Flint works as expected for them, before we start asking end
> users/distributions to start testing.
>
> We have made many modifications since alpha1, including:
>
> * removing all known memory leaks
> * fixing a bug in the integer gcd (leak, inefficiency, very slim
> chance of wrong answer)
> * properly supporting GMP-6.2
> * making matrices with zero rows/columns more robust
> * many other less important fixes (35 commits total)
> * fixing a bug/crash in the _f functions in the fmpz_mod_poly module
>

OK, so now it passes on everything I tried it on (most exotic:
clang-8.0.1 on OpenBSD, with NTL enabled)
Will now try to test it with Sage (https://trac.sagemath.org/ticket/29719)


> We don't foresee the need for any further alpha releases, (assuming no
> major issues are found). The next release will likely either be a beta
> or release candidate. Please note the only important things that
> remain to be done as far as we know are documentation/paperwork
> related [2].
>
> Please report bugs on our GitHub issue tracker. Successful builds can
> be reported here.
>
> Best Wishes,
>
> The Flint Development Team
>
> P.S. thanks to the Flint package maintainer in the Fedora project who
> did early reporting/patching of many issues and to the numerous people
> who gave feedback on the first alpha! Many more acknowledgements to
> come in the release announcement!
>
> [1] https://github.com/wbhart/flint2
> [2] https://github.com/wbhart/flint2/milestone/2
>
> --
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[sage-devel] Re: Are complex numbers ordered?

[Bruce Westbury]

Thank you for the replies.

It seems to me, from reading the replies, that, although this order is not 
natural from a mathematical point of view, there are programming reasons 
for it.
I am not in a position to assess these reasons but the fact that this 
comparison has been dropped in Python 3 suggests they are surmountable.

There is therefore a case for deprecating this (and similar) orders. 
However deprecating means the feature will be removed so this would require
alternatives. I have done a grep search on sage/src for_cmp_, __cmp__ and 
__richcmp__ and there seemed to only a few places where these are used.
I personally do not have the experience to pursue this.

An alternative would be to expand the category framework. The only 
categories for orderings I can see are OrderedMonoids, 
PartiallyOrderedMonoids.
We could also have (Partially)OrderedRings. I would consider opening a 
ticket for this but I would like to know if there is support for this
(both moral and practical). I suspect I am being naive about what is 
involved here.

Independently of these, there is an indisputable case for the thankless 
task of improving the documentation.

On Wednesday, 20 May 2020 22:12:02 UTC+1, Bruce Westbury wrote:
>
> This was unexpected
>
> {{{
> sage: CC(I) > CC(0)
> True
> sage: CC(-I) > CC(0)
> False
> }}}
>
> Are these the intended results?
>

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