[sage-devel] Re: Multiple warnings in sagemath on default fedora 37
Hi, Le vendredi 20 janvier 2023 à 06:26:38 UTC+1, Georgi Guninski a écrit : sage: integrate(floor(x)^2,x) // Giac share root-directory:/usr/share/giac/ // Giac share root-directory:/usr/share/giac/ Added 0 synonyms x*floor(x)^2 I get this one with Sage 9.8.beta7 built from source on Ubuntu. So it is not a Fedora packaging issue. Eric. -- 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/34708034-f732-4b4a-9682-13039658ca56n%40googlegroups.com.
[sage-devel] Doubts about correctness of `integrate(floor(x)^2,x)`
I have theoretical reasons to doubt the correctness of integrals involving `floor`. The smallest testcases: sage: integrate(floor(x)^2,x) // Giac share root-directory:/usr/share/giac/ // Giac share root-directory:/usr/share/giac/ Added 0 synonyms x*floor(x)^2 sage: integrate(2**floor(x),x) 2^floor(x)*x Would someone check with another CAS or prove/disprove by hand? -- 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/CAGUWgD8C_AeV31g3J%2BbQP-am7dKUj2gK1OzPYrqXMiPh8-y5JQ%40mail.gmail.com.
Re: [sage-devel] Re: Please inspect: Migrated Trac tickets on our temporary GitHub server
In the latest iteration,
https://34.105.185.241/sagemath/sage-all-2023-01-14-009/issues, I have
switched to the shorter prefix "c: " for components.
Regarding the component labels, we have an ongoing discussion
in https://github.com/sagemath/trac-to-github/issues/99
On Tuesday, January 17, 2023 at 11:08:15 AM UTC-8 Matthias Koeppe wrote:
> On Tuesday, January 17, 2023 at 2:10:24 AM UTC-8 john.c...@gmail.com
> wrote:
> I think it is fine to have many different labels for issues, as we have
> many components. But why was it thought necessary to have all the
> component labels start with "component:"? That seems redundant. It does
> mean that all the components come almost first in the list of labels ("bug"
> is at the top which is fine), with the dozen or so non-component labels
> other than bug all at the bottom of the list. If we could prefix all the
> non-component labels instead with something very small which was allowed by
> GitHub and which made them all come first, then we could remove the
> "component:" prefix from the majority.
>
> Controlling the sort order in the drop down list of the Issues UI was the
> reason for using label prefixes. That's why we have "component: " as well
> as "p1 –" "p5 – " for the priority.
>
> Tobias' initial proposal was to use the single letter "c: " as the prefix
> for components. I thought it would be too cryptic, so I went with the whole
> word "component: ". But I'd be happy to change it if "c: " (or some other
> idea) seems preferable to others.
>
>
>
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Re: [sage-devel] Doubts about correctness of `integrate(floor(x)^2,x)`
On Fri, Jan 20, 2023 at 07:16:14PM +0200, Georgi Guninski wrote:
> I have theoretical reasons to doubt the correctness
> of integrals involving `floor`.
>
> The smallest testcases:
>
> sage: integrate(floor(x)^2,x)
> // Giac share root-directory:/usr/share/giac/
> // Giac share root-directory:/usr/share/giac/
> Added 0 synonyms
> x*floor(x)^2
>
> sage: integrate(2**floor(x),x)
> 2^floor(x)*x
>
> Would someone check with another CAS or prove/disprove by hand?
Maple reports the same result for your first testcase:
tux% maple
|\^/| Maple 2022 (X86 64 LINUX)
._|\| |/|_. Copyright (c) Maplesoft, a division of Waterloo Maple Inc. 2022
\ MAPLE / All rights reserved. Maple is a trademark of
< > Waterloo Maple Inc.
| Type ? for help.
> int(floor(x)^2, x);
2
floor(x) x
>
But, I think Maple and Sage/Giac are both wrong: consider the *definite*
integral (latex notation) $I = \int_0^{3/2} \lfloor x \rfloor^2 \, dx$:
Then the Sage/Giac indefinite integral implies that
$I = \left. x \lfloor x \rfloor^2 \right|^{3/2}_0
= (3/2) \lfloor (3/2) \rfloor^2 - 0 \lfloor 0 \rfloor^2
= 3/2$
But it seems to me that the correct result should be
$I = \int_0^{3/2} \lfloor x \rfloor^2 \, dx$
= \int_0^1 \lfloor x \rfloor^2 \, dx
+ \int_1^{3/2} \lfloor x \rfloor^2 \, dx
= \int_0^1 0 \, dx + \int_1^{3/2} 1 \, dx
= 0 + 1/2
= 1/2$
--
-- "Jonathan Thornburg [remove -color to reply]"
on the west coast of Canada
"Now back when I worked in banking, if someone went to Barclays,
pretended to be me, borrowed UKP10,000 and legged it, that was
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