Hi Emmanuel,
On 2019-10-24, Emmanuel Charpentier wrote:
> Writing *correctly* this decomposition is, IIRC, a numerical analysis
> bitch... You are, IIRC, led to compute differences of large products, where
> underflows can easily slip into... Definitely not an amateur's problem.
>
> While I
Dear Michael
Contrast
sage: A=matrix(QQ,[[1, 2], [3,4]])
sage: G,M=M.gram_schmidt()
sage: A=matrix(QQ,[[1, 2], [3,4]])
sage: G,M=A.gram_schmidt()
sage: M*G==A
True
with
sage: Ar=matrix(RDF,[[1, 2], [3,4]])
sage: Gr,Mr=Ar.gram_schmidt()
sage: Mr*Gr==Ar
False
sage: Mr*Gr-A
I see. Maybe it is possible to decompose/split the matrix in SR into an exact
and inexact part, convert the inexact part to RDF and apply the Gram-Schmidt
algorithm appropiately? I don't know, maybe it's too naive?
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On Thursday, October 24, 2019 at 11:23:02 AM UTC-7, Dima Pasechnik wrote:
>
>
> I am thinking that having a cross-platform
>
> sage_ctypes=ctypes.cdll.LoadLibrary("...")
>
> mihgt be useful to have beyond 1 test...
>
I think so too, but if you google a bit you see there are various wrappers
On Thu, Oct 24, 2019 at 7:15 PM John H Palmieri wrote:
>
>
>
> On Thursday, October 24, 2019 at 10:57:09 AM UTC-7, Dima Pasechnik wrote:
>>
>> On Thu, Oct 24, 2019 at 6:48 PM Nils Bruin wrote:
>> >
>> > On Thursday, October 24, 2019 at 10:29:48 AM UTC-7, Nils Bruin wrote:
>> >>
>> >>
>> >> I
On Thursday, October 24, 2019 at 10:57:09 AM UTC-7, Dima Pasechnik wrote:
>
> On Thu, Oct 24, 2019 at 6:48 PM Nils Bruin >
> wrote:
> >
> > On Thursday, October 24, 2019 at 10:29:48 AM UTC-7, Nils Bruin wrote:
> >>
> >>
> >> I guess via ctypes it would be possible too.
> >
> >
> >
On Thu, Oct 24, 2019 at 6:48 PM Nils Bruin wrote:
>
> On Thursday, October 24, 2019 at 10:29:48 AM UTC-7, Nils Bruin wrote:
>>
>>
>> I guess via ctypes it would be possible too.
>
>
> Browsing the documentation, something like:
>
> libc=ctypes.cdll.LoadLibrary("libc.so.6")
> libc.fflush(0r)
>
>
On Thursday, October 24, 2019 at 10:29:48 AM UTC-7, Nils Bruin wrote:
>
>
> I guess via ctypes it would be possible too.
>
Browsing the documentation, something like:
libc=ctypes.cdll.LoadLibrary("libc.so.6")
libc.fflush(0r)
should work. And this should cause way less overhead than calling
On Thursday, October 24, 2019 at 8:39:00 AM UTC-7, John H Palmieri wrote:
>
>
> So maybe it should be on stderr, but it's not. Regarding
> sys.stdout.flush(), my understanding, as confirmed by my experience with
> this particular problem, is that this only flushes output coming from
> Python,
On 2019-10-24, Michael Jung wrote:
> Do you have an example where SR fails to be exact?
One can convert a float to SR. The result is in SR, but still behaves
like a float:
sage: a = SR(2.)^(1/500)
sage: a^500
2.05
sage: a.parent()
Symbolic Ring
Best regards,
Simon
--
You
Do you have an example where SR fails to be exact?
Am Donnerstag, 24. Oktober 2019 18:20:36 UTC+2 schrieb Simon King:
>
> Hi Michael,
>
> On 2019-10-24, Michael Jung > wrote:
> > Maybe, I did get something wrong. But what's the problem about
> Gram-Schmidt
> > on SR? There are just sums and
Hi Michael,
On 2019-10-24, Michael Jung wrote:
> Maybe, I did get something wrong. But what's the problem about Gram-Schmidt
> on SR? There are just sums and divisions (and probably roots to normalize)
> in Gram-Schmidt which should not lead to problems in SR.
>
> By the way, what does "exact"
Maybe, I did get something wrong. But what's the problem about Gram-Schmidt
on SR? There are just sums and divisions (and probably roots to normalize)
in Gram-Schmidt which should not lead to problems in SR.
By the way, what does "exact" actually mean?
Am Mittwoch, 23. Oktober 2019 22:41:53
On Wednesday, October 23, 2019 at 9:49:56 PM UTC-7, Nils Bruin wrote:
>
> On Wednesday, October 23, 2019 at 2:47:54 PM UTC-7, John H Palmieri wrote:
>>
>>
>>
>> On Wednesday, October 23, 2019 at 1:41:35 PM UTC-7, Nils Bruin wrote:
>>>
>>> On Wednesday, October 23, 2019 at 1:26:46 PM UTC-7, John
Le mercredi 23 octobre 2019 19:46:10 UTC+2, Pong a écrit :
>
> Sorry for jumping the gun.
>
> The improved version is
> sage.plot.multigraphics.GraphicsArray(array)
>
>
> http://doc.sagemath.org/html/en/reference/plotting/sage/plot/multigraphics.html#module-sage.plot.multigraphics
>
>
For the
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