Re: [sage-devel] zero division
On 2016-03-09 23:56, Thierry wrote: Willing to change the behaviour will be similar to requesting that 'NaN in RR' should return False. Not the topic of this thread, but I really think that "NaN in RR" should return False. RR represents the real numbers and NaN is *not a number*. Note that Sage usually defines "x in P" as "P(x) == x" which would actually give False for NaN since NaN != NaN. Whether Infinity should be in RR is a more borderline question, but I don't mind that RR(1)/RR(0) gives Infinity. -- 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 post to this group, send email to sage-devel@googlegroups.com. Visit this group at https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
[sage-devel] Re: log(8) == 3*log(2)
Funnier than what I thought initially sage: for i in range(20): :print i, bool(log(2**i) / log(2) == ZZ(i)) 0 True 1 True 2 True 3 False 4 True 5 True 6 False 7 False 8 True 9 True 10 True 11 False 12 False 13 True 14 False 15 True 16 True 17 False 18 True 19 False On 09/03/16 23:41, Vincent Delecroix wrote: Hello, In the current beta I have sage: bool(log(8) == 3*log(2)) False Why Sage is not able to check this simple relation directly? Hopefully, sage: bool((log(8) == 3*log(2)).simplify_log()) True But not very convenient. Best, Vincent -- 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 post to this group, send email to sage-devel@googlegroups.com. Visit this group at https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
[sage-devel] log(8) == 3*log(2)
Hello, In the current beta I have sage: bool(log(8) == 3*log(2)) False Why Sage is not able to check this simple relation directly? Hopefully, sage: bool((log(8) == 3*log(2)).simplify_log()) True But not very convenient. Best, Vincent -- 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 post to this group, send email to sage-devel@googlegroups.com. Visit this group at https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
Re: [sage-devel] zero division
Hi Vincent, On Wed, Mar 09, 2016 at 10:44:10AM -0500, David Roe wrote: > The behavior for floating point is governed by IEEE standards, which > dictate +infinity in this case. So I think this is not a bug. I strongly agree with this point of view! Elements belong to some parent, which has some rules and expected bahaviour. In your zeroth case, 1 and 0 belong to the integer ring ZZ, where 1/0 is not defined. This is consistent with AA(1)/AA(0), QQ(1)/QQ(0), etc... In your first case, 1. and 0. belong to RR, which is the set of MPFR elements, for which 1./0. is specified by IEEE standards. Willing to change the behaviour will be similar to requesting that 'NaN in RR' should return False. Though many people are not convinced, i think such confusion shows again the need for a genuine mathematical Real Field abstraction which i somtimes advocate, over the existing representations, containing QQbar(2).sqrt() as well as pi, 1/3 and 0.1, in which 1./0. raises an error, because this is what makes sense in this parent. In your second case, well, SR behaviour is not specified, so i have no particular expectation ;) In your third case, you say "I guess that the behavior of Sage floating point should be modified. What do you think?". It depends on which level you are asking. Somehow, it is already the case, Sage floats are Python floats: sage: float(1.)/float(0.) ZeroDivisionError: float division by zero For RDF or RR, it is not a good option as explained before. But perhaps (i am not sure about your actual query), you are asking for the default *preparsing* of "0.1", which could be left unparsed by default (hence being a Python float with the behaviour you want). This is very tempting. Indeed, during a tutorial i gave one year ago at Paris 13, a few numericians were there, and while trying to work with numpy/sympy following some tutorial, they surrended because of the preparsing of floating-point that was not compatible with standard Python and did not allow to work with numpy/sympy examples, and they all finally went to install anaconda instead. Not being comparible with the Python ecosystem is an issue. Said otherwise: newcomers-friendlyness should not be part of the code but located on a specific "interface" layer (and made visible and explicit). Ciao, Thierry > On Mar 9, 2016 10:13, "Vincent Delecroix" <20100.delecr...@gmail.com> wrote: > > > Hello, > > > > Compare > > > > > > sage: 1 / 0 > > Traceback (most recent call last): > > ... > > ZeroDivisionError: rational division by zero > > > > > > sage: 1. / 0. > > +infinity > > > > > > sage: SR(1.) / SR(0.) > > Traceback (most recent call last): > > ... > > ZeroDivisionError: Symbolic division by zero > > > > > > Since in Python (2 and 3) we have > > > > sage: 1.r / 0.r > > Traceback (most recent call last): > > ... > > ZeroDivisionError: float division by zero > > > > I guess that the behavior of Sage floating point should be modified. What > > do you think? > > > > Vincent > > > > -- > > 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 post to this group, send email to sage-devel@googlegroups.com. > > Visit this group at https://groups.google.com/group/sage-devel. > > For more options, visit https://groups.google.com/d/optout. > > > > -- > 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 post to this group, send email to sage-devel@googlegroups.com. > Visit this group at https://groups.google.com/group/sage-devel. > For more options, visit https://groups.google.com/d/optout. -- 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 post to this group, send email to sage-devel@googlegroups.com. Visit this group at https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
Re: [sage-devel] make ptestlong and binary-pkg
On 2016-03-07 09:36, Daniel Krenn wrote: > 2) Some of the doctests fail, for example: > > File "src/sage/lfunctions/lcalc.py", line 376, in > sage.lfunctions.lcalc.LCalc.analytic_rank > Failed example: > lcalc.analytic_rank(E) > Expected: > 1 > Got: > *** Warning: can't expand ~. > *** Warning: can't expand ~. > 1 I've tested again and now the problem is gone (it was related to network and filesystem mounting issues on my system). Daniel -- 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 post to this group, send email to sage-devel@googlegroups.com. Visit this group at https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
Re: [sage-devel] make ptestlong and binary-pkg
On 2016-03-07 09:36, Daniel Krenn wrote: > I've used https://github.com/sagemath/binary-pkg to create a package > sage-7.1.beta6-Ubuntu_14.04-x86_64.tar.bz2 > Then I've extracted it to some location; relocating (once) seem to have > worked, but with the following issues (with make ptestlong): > > 1a) Before running the tests, all the cythonized files are compiled again. > > 1b) Similarly, the full documentation seems to be rebuilt. Does someone know how to fix these issues? It would be great to be able to use my own binary for development (since relocating is gone...) Best wishes Daniel -- 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 post to this group, send email to sage-devel@googlegroups.com. Visit this group at https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
Re: [sage-devel] Re: Bye
Note that I wasn't saying anything about Nathann's opinions, and I even said that some of them were valuable. We could / should debate many things, and I think these debates happen (as William pointed out about the name). I was mostly defending myself against a false accusation as I am part, I guess, of "Nicolas and his team". What I was saying is the way Nathann raises these questions, and gives his opinion in general, is often offending in many ways (it has been towards me multiple times and towards lots of other people) which is bad for the community on the long term because we loose valuable contributions. And if he's not able to do it in an other way, then I prefer him gone even if this means we loose a good developer. If whenever you do "something", either a promotional video or a track ticket or whatever, you take the risk of being accused, attacked, or even insulted, then the conclusion is you do nothing ever again: no risk taken! And some people have started to go this way. >From Nathann's message, I understand he believes many people in Sage work mostly for their personal interests against the community, "exploiting" his own work. I think this is completely false and that he is in no place to make such an accusation. But if it is what he truly believes, then, yes, he should leave and stop this recurrent accusations. And it will be better for us. Best Viviane 2016-03-09 16:05 GMT+01:00 Vincent Delecroix <20100.delecr...@gmail.com>: > Hello, > > One point I think Nathann has right and was not discussed further is the > fact that Sage the distribution is tightly linked to Sage the company. Some > examples: > - the "forced" change of names by William from Sage to SageMath when the > company is SageMath Inc. > - websites: sagemath.org for the distribution whereas sagemath.com for > the company > - loud advertising from sagemath.org > > I feel great that SageMath Inc exists. And I think that it proposes a > useful service especially concerning collaborative work. But I would feel > better if it was either more collaboratively discussed (e.g. at the same > level that Sage code is discussed). Or more disconnected from Sage the > distribution (e.g. not playing with the *.org vs *.com). > > Moreover, the cloud service proposed by SageMath Inc is much more than > just Sage. It would have been natural to choose an other name from the > beginning. > > Best, > Vincent > > > On 26/02/16 10:58, mmarco wrote: > >> Wow, this whole discussion, and the subsequent thread opened by William >> have really blown my mind a little bit. >> >> I disagree with most of the objections raised by Nathann. I have to say >> that the impression I got from them at the beginning have changed as the >> discussion has evolved and his points have been clarified. I also dislike >> his (sometimes aggresive, sometimes disrispectful) style when writing in >> this group. >> >> But I really respect the fact that he takes a moral position about what he >> considers to be an ethical problem. And I am really happy that he has >> raised these questions, and that we have had this discusion. As Rogaway >> [1] >> recently stated, it is important that we, scientists, take into >> consideration the moral implications of our work; so I am literally >> delighted to see a discussion about the morality of what we do in >> sage-devel. >> >> At the beginning, I thought that the main problem that Nathan was pointing >> to had to do with the money. The fact that somebody (he particularizes in >> William, but also makes some comments about the OpenDreamKit grant) makes >> money using the Sage code was -or I thought it was- thecore moral problem. >> I don't agree with that view, for a couple of reasons: >> >> 1) All Sage code is GPL'ed, which means not only that everybody has the >> legal right to use it as apart as a business model (provided the >> conditions >> of the GPL are respected); but also that the people that wrote that code >> have given an explicit permission to do so. The fact that the use of Sage >> code in SMC is legal is not the consequence of some loophole in the law. >> It >> is the consequence of the explicit permission of the code writers to >> everybody that wants to use the code with basically the only condition of >> not relicensing it. That clearly includes the kind of use that SMC does, >> so >> I definitely see no moral problem there. William can use my code in SMC >> because I explicitely gave him (and everybody else) permission to use it >> in >> that way (and many other possible ways too). Same applyes for the rest of >> the developpers. >> >> 2) If we to to a lower level in the moral discussion, and leaving law >> aside, we get to the point of the morality of copyright and intellectual >> property in general: which are the possible ethical uses of other people's >> immaterial creations? The most extended line of thought (and it is the one >> in which the copyright laws -and hence the software licenses- are based) >> is >>
Re: [sage-devel] Re: Bye
On 09/03/16 13:08, William Stein wrote: On Wed, Mar 9, 2016 at 7:05 AM, Vincent Delecroix <20100.delecr...@gmail.com> wrote: One point I think Nathann has right and was not discussed further is the fact that Sage the distribution is tightly linked to Sage the company. Some examples: - the "forced" change of names by William from Sage to SageMath Let me remind you that the name change was publicly discussed, during which *you* said "[...] Good idea. The current situation is confusing." https://groups.google.com/forum/#!searchin/sage-devel/sagemath$20change/sage-devel/UCfXO7BlyEc/r_A8F-inxx0J And my opinion somehow changed because of events I did not knew at that time. Note that the "confusion" I had was "Sage the math software" versus "Sage the financial software". Let me also remind that your argumentation for the name change was (cf first message of the thread): "Sage is used too much" (that I still fully agree with) and not "I want to use the name SageMath for my company and it would be nice to use the same name for the software". This is what I wanted to criticized in my message. I hope this make it clearer. Moreover, the cloud service proposed by SageMath Inc is much more than just Sage. The mission statement of the SageMath project is create a viable free open source alternative to Magma, Maple, Mathematica, and Matlab. Which SageMath? What are the actual implications of a mission statement? For me it is like a jingle, ie just for marketing. Vincent -- 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 post to this group, send email to sage-devel@googlegroups.com. Visit this group at https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
Re: [sage-devel] Re: Bye
On Wed, Mar 9, 2016 at 7:05 AM, Vincent Delecroix <20100.delecr...@gmail.com> wrote: > One point I think Nathann has right and was not discussed further is the > fact that Sage the distribution is tightly linked to Sage the company. Some > examples: > - the "forced" change of names by William from Sage to SageMath Let me remind you that the name change was publicly discussed, during which *you* said "[...] Good idea. The current situation is confusing." https://groups.google.com/forum/#!searchin/sage-devel/sagemath$20change/sage-devel/UCfXO7BlyEc/r_A8F-inxx0J > Moreover, the cloud service proposed by SageMath Inc is much > more than just Sage. The mission statement of the SageMath project is create a viable free open source alternative to Magma, Maple, Mathematica, and Matlab. -- William (http://wstein.org) -- 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 post to this group, send email to sage-devel@googlegroups.com. Visit this group at https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
Re: [sage-devel] zero division
The behavior for floating point is governed by IEEE standards, which dictate +infinity in this case. So I think this is not a bug. On Mar 9, 2016 10:13, "Vincent Delecroix" <20100.delecr...@gmail.com> wrote: > Hello, > > Compare > > > sage: 1 / 0 > Traceback (most recent call last): > ... > ZeroDivisionError: rational division by zero > > > sage: 1. / 0. > +infinity > > > sage: SR(1.) / SR(0.) > Traceback (most recent call last): > ... > ZeroDivisionError: Symbolic division by zero > > > Since in Python (2 and 3) we have > > sage: 1.r / 0.r > Traceback (most recent call last): > ... > ZeroDivisionError: float division by zero > > I guess that the behavior of Sage floating point should be modified. What > do you think? > > Vincent > > -- > 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 post to this group, send email to sage-devel@googlegroups.com. > Visit this group at https://groups.google.com/group/sage-devel. > For more options, visit https://groups.google.com/d/optout. > -- 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 post to this group, send email to sage-devel@googlegroups.com. Visit this group at https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
[sage-devel] zero division
Hello, Compare sage: 1 / 0 Traceback (most recent call last): ... ZeroDivisionError: rational division by zero sage: 1. / 0. +infinity sage: SR(1.) / SR(0.) Traceback (most recent call last): ... ZeroDivisionError: Symbolic division by zero Since in Python (2 and 3) we have sage: 1.r / 0.r Traceback (most recent call last): ... ZeroDivisionError: float division by zero I guess that the behavior of Sage floating point should be modified. What do you think? Vincent -- 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 post to this group, send email to sage-devel@googlegroups.com. Visit this group at https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
Re: [sage-devel] Re: Bye
Hello, One point I think Nathann has right and was not discussed further is the fact that Sage the distribution is tightly linked to Sage the company. Some examples: - the "forced" change of names by William from Sage to SageMath when the company is SageMath Inc. - websites: sagemath.org for the distribution whereas sagemath.com for the company - loud advertising from sagemath.org I feel great that SageMath Inc exists. And I think that it proposes a useful service especially concerning collaborative work. But I would feel better if it was either more collaboratively discussed (e.g. at the same level that Sage code is discussed). Or more disconnected from Sage the distribution (e.g. not playing with the *.org vs *.com). Moreover, the cloud service proposed by SageMath Inc is much more than just Sage. It would have been natural to choose an other name from the beginning. Best, Vincent On 26/02/16 10:58, mmarco wrote: Wow, this whole discussion, and the subsequent thread opened by William have really blown my mind a little bit. I disagree with most of the objections raised by Nathann. I have to say that the impression I got from them at the beginning have changed as the discussion has evolved and his points have been clarified. I also dislike his (sometimes aggresive, sometimes disrispectful) style when writing in this group. But I really respect the fact that he takes a moral position about what he considers to be an ethical problem. And I am really happy that he has raised these questions, and that we have had this discusion. As Rogaway [1] recently stated, it is important that we, scientists, take into consideration the moral implications of our work; so I am literally delighted to see a discussion about the morality of what we do in sage-devel. At the beginning, I thought that the main problem that Nathan was pointing to had to do with the money. The fact that somebody (he particularizes in William, but also makes some comments about the OpenDreamKit grant) makes money using the Sage code was -or I thought it was- thecore moral problem. I don't agree with that view, for a couple of reasons: 1) All Sage code is GPL'ed, which means not only that everybody has the legal right to use it as apart as a business model (provided the conditions of the GPL are respected); but also that the people that wrote that code have given an explicit permission to do so. The fact that the use of Sage code in SMC is legal is not the consequence of some loophole in the law. It is the consequence of the explicit permission of the code writers to everybody that wants to use the code with basically the only condition of not relicensing it. That clearly includes the kind of use that SMC does, so I definitely see no moral problem there. William can use my code in SMC because I explicitely gave him (and everybody else) permission to use it in that way (and many other possible ways too). Same applyes for the rest of the developpers. 2) If we to to a lower level in the moral discussion, and leaving law aside, we get to the point of the morality of copyright and intellectual property in general: which are the possible ethical uses of other people's immaterial creations? The most extended line of thought (and it is the one in which the copyright laws -and hence the software licenses- are based) is that such a use is ethical as long as it is done with the permission of the author. The author has some kind of natural right to decide who and how can use his/her creations. I disagree with this view (and I know i am probably alone in this). The idea that somebody in the other side of the world cannot make use of a idea just because I had that idea before, and wrote it down sounds ridiculous to me. The idea or property is bounded to the limitation of the objects of that property: we need a criterion to decide who does an apple belong to because it can only be eaten once. In the immaterial world of mind creations, there is not such limitation, so the concept of property really makes no sense: we only accept it because it is what we are used to. Ideas should be freely shared and used. As should software, texts, songs and any other immaterial goods. We, as a society, can decide to put some regulations on this in the basis that they would cause people to behave in a way that we consider to be better for us in the long term; but that is not based on moral anymore: that is based on convenience (which might be a good idea, but it is not a moral mandate). So, from my point of view in this aspect, there wouldn't be any moral problem in the use of Sage code that SMC does either. At some point, Nathann rephrased his complains, and then I realized that I hadn't correctly understood his reasons. He claims that the main problem is the fact that the decission of starting SMC was taken without considering the sage developper's community. I think he is partly right about this: it could have been a better idea to try this step as
Re: [sage-devel] Re: I think my students hate me
> > > > I do have a basement but it's definitely not a place to do Sage, and in > any > > case have found trains to be an effective place to work on Sage, if the > > wireless is working... > > Who needs wireless? I thought that was what git was good for ;) > Haha! But eventually one needs to use git push ;-) -- 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 post to this group, send email to sage-devel@googlegroups.com. Visit this group at https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
[sage-devel] Re: Bye
I don't know you... But I have come to need SMC : I don't use windows ! I was very reluctant to use it because I don't like to work on internet. But it's such a great application and specially nowadays I can work with vpython and ivisual ! My wish for so many years and no more windaube ! (lol) Sorry but my joy is great... I tried to educate many young people (a group we call "disfavorised" in pschylogical term) for about 20 years and when I used electronic and computing ( year 88, in france that's was the very beginning) I saw an opportunity to help efficiently some youngs who liked this kind of things. Open source is the best creation made by man... Capitalism is the worse ! Enjoy yourself :) Henri On Monday, February 22, 2016 at 7:47:54 PM UTC+1, Nathann Cohen wrote: > > Hello everybody, > > I am disgusted by what this community has become. You are also tired > of seeing me complain here about a lot of things. > > Have fun. > > Nathann > -- 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 post to this group, send email to sage-devel@googlegroups.com. Visit this group at https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
Re: [sage-devel] Re: Bye
Dear all, I answer this thread only now as I haven't had much time to read sage-devel these past days. First, I must say that I feel very offended my Nathann public implication that by being part of ODK I "build my career on other people's work". Nathann, I think you have absolutely no idea what my career is built on, what my work is and what I have done and still do for Sage (not everything is trac tickets). Second, if you suffer that much doing Sage, then well, just stop doing it. The great thing about working in research (with a permanent position) and open-source is that no one if forcing you to do anything. Now, many people have said that they will miss your contributions and you take that as a proof that you are being exploited. Well see, I value your work as a developer but I think the way you interact with people is toxic for the community. So if you cannot contribute without being toxic, I would rather have you not contributing (and it won't affect my career!!). This is only my opinion and I don't ask the community to back me up. I would just want to point out that even though Nathann sometimes express valuables opinions, the way he express them has lead many other valuable contributors to stop talking on the mailing list. And because you could also get attacked for contributing to a ticket, I'm pretty sure (even though I have no evidence) that we have lost valuable contributions to Sage because the person willing to do the contribution wouldn't bother arguing with Nathann: I would never dream of touching the graph package a bit even if it lacked a key feature I needed. So well, Nathann, as much as I appreciate you as a person, I don't believe you're in the right place now to contribute to an open-source community. Saying this, I wish you the best in whatever you do and I hope we can find ways as a community to avoid toxic behaviors and a better way to deal with such things in a future, which wouldn't end by us loosing many contributors (you + the ones you offended too much). Best Viviane 2016-02-26 14:58 GMT+01:00 mmarco : > Wow, this whole discussion, and the subsequent thread opened by William > have really blown my mind a little bit. > > I disagree with most of the objections raised by Nathann. I have to say > that the impression I got from them at the beginning have changed as the > discussion has evolved and his points have been clarified. I also dislike > his (sometimes aggresive, sometimes disrispectful) style when writing in > this group. > > But I really respect the fact that he takes a moral position about what he > considers to be an ethical problem. And I am really happy that he has > raised these questions, and that we have had this discusion. As Rogaway [1] > recently stated, it is important that we, scientists, take into > consideration the moral implications of our work; so I am literally > delighted to see a discussion about the morality of what we do in > sage-devel. > > At the beginning, I thought that the main problem that Nathan was pointing > to had to do with the money. The fact that somebody (he particularizes in > William, but also makes some comments about the OpenDreamKit grant) makes > money using the Sage code was -or I thought it was- thecore moral problem. > I don't agree with that view, for a couple of reasons: > > 1) All Sage code is GPL'ed, which means not only that everybody has the > legal right to use it as apart as a business model (provided the conditions > of the GPL are respected); but also that the people that wrote that code > have given an explicit permission to do so. The fact that the use of Sage > code in SMC is legal is not the consequence of some loophole in the law. It > is the consequence of the explicit permission of the code writers to > everybody that wants to use the code with basically the only condition of > not relicensing it. That clearly includes the kind of use that SMC does, so > I definitely see no moral problem there. William can use my code in SMC > because I explicitely gave him (and everybody else) permission to use it in > that way (and many other possible ways too). Same applyes for the rest of > the developpers. > > 2) If we to to a lower level in the moral discussion, and leaving law > aside, we get to the point of the morality of copyright and intellectual > property in general: which are the possible ethical uses of other people's > immaterial creations? The most extended line of thought (and it is the one > in which the copyright laws -and hence the software licenses- are based) is > that such a use is ethical as long as it is done with the permission of the > author. The author has some kind of natural right to decide who and how can > use his/her creations. I disagree with this view (and I know i am probably > alone in this). The idea that somebody in the other side of the world > cannot make use of a idea just because I had that idea before, and wrote it > down sounds ridiculous to me. The idea or property is
[sage-devel] Re: RedHat/opensource.com -- article about Sage
Le mardi 8 mars 2016 18:46:29 UTC+1, William a écrit : > > Hi Sage Devs, > > See > > https://opensource.com/education/16/3/sagemath > > and > > http://lwn.net/ > > Don't expect anything interesting to *you* -- it's just basically the > transcript of that video my brother made, which has no "real content". > However, the video is making many people aware of Sage who had never > heard of it before. For example, I just got this email: "... I > learned about SageMath today thanks to your article (2) and already > explored it with a student of meteorology, we were both hugely > impressed by the scale of SageMath. ..." > > -- William > Nice. For future reference (in case it leaves the front page after some time), the lwn.net article is at http://lwn.net/Articles/679172/ -- 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 post to this group, send email to sage-devel@googlegroups.com. Visit this group at https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
[sage-devel] Re: Query about SageMath for GSOC
Actually the idea per se is not so bad but you would use a separate system like PRESS: http://dream.inf.ed.ac.uk/software/press/ This would need to be made a Sage package and be interfaced as usual. Regards,. -- 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 post to this group, send email to sage-devel@googlegroups.com. Visit this group at https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
Re: [sage-devel] Query about SageMath for GSOC
> For example: We have an equation (2+3*(8/2)) and when I solve this
> equation in SageMath it gives the exact answer i.e 14. However, it's
> really interesting to imagine if Sage prints all the steps that how
> they solve the above equation to find its answer like first it print
> this (2+3*4) by solving inner bracket and then it print (2+12) by
> multiplying 3 and 4 and at least it prints the last answer i.e 14.
> This can be done by using BODMAS rule. If by some algorithm or
> logic Sage prints every step of BODMAS operation then Sage have the
> capability to prints
> all the steps that how they solve the particular equation.
Hi Amritpal,
It sounds to me like you mean "computation of expressions" and not
"solving equations". The difference is that "solving an equation" is
e.g. finding x under the requirement that
x^2 - 2*x + 1 = 0 ,
i.e. something that contains at least one unknown x. For solving the
above equation in x, one *could* write something like
x^2 - 2*x + 1 = 0 <=>
(x-1)^2 = 0 <=>
x-1 = 0
but more likely, the backend system will just apply the closed formula
for solving a second-degree equation, which would give the somewhat less
enlightening derivation
x^2 - 2*x + 1 = 0 =>
x = -(-2)/(2*1) +- sqrt((-2)^2 - 4 * 1 * 1)/(2*1) <=>
x = 1
In other words, there's two major problems with asking a system like
Sage to write out the derivation in solving an equation:
1) A derivation useful for a computer is often not the most readable or
useful for a human.
2) Most non-obvious computations will be done using complicated
algorithms - not even formulas - whose intermediate steps would not hold
much sense for a human to read.
If we restrict ourselves to "computation of expressions" like what
you're actually writing about, then you seem to basically suggest:
- writing out the BNF form of a computation tree, e.g. (2+3*8/2) could
be written
+
2 *
3/
8 2
- The expression should now be computed by simplifying nodes which have
only leaves as children. In the above there is only one choice, namely
the "/".
- After each such simplification, print the new expression (flattening
the updated BNF back to a string, with the necessary parentheses added).
Since Sage uses various backends for the actual computations, and
simplifies in many different locations, it won't be easy to modify Sage
itself to do this everywhere. I also don't think that would be a
particularly sensible option for Sage.
However, it could be achieved, I think, by working on the level of
strings:
sage: print_computation("2+3*8/2")
2+3*8/2
2+3*4
2+12
14
The print_computation function thus takes a *string*, and it has
complete control over when the computations should take place. The
print_computation function could be implemented by scanning over the
string, emulating (or using?) the Python parser, and constructing the
BNF expression tree. The print_computation would then itself carry out
the computation step-wise and printing every time, instead of hacking
into the rest of Sage.
Note that this should be extendable to also allow more complicated Sage
objects to be printed:
sage: M = matrix(ZZ, [ 1, 2, 3, 4])
sage: print_computation('(3 * M) * M')
[1 2] [1 2]
(3 * [3 4] ) * [3 4]
[3 6] * [1 2]
[9 12] [3 4]
[21 30]
[45 66]
(it could probably be typeset better, though)
However, I'm not convinced such a functionality is really super-cool and
important to have in Sage? As Ralf pointed out, at this level, you could
achieve it manually without too much trouble, so why should Sage offer
the functionality internally -- how often will it be used?
A related, and mathematically quite important feature, is that of
"certificates": that a function returns together with its output a
certificate, a kind of proof, that output is really correct. For
instance, say I call M.rank() on a matrix M. How do I know that the
output 5 is correct? It would be nice to have a proof that I could
check, possibly in a probabilistic way, and preferably much faster than
the rank computation itself, to be certain that 5 is indeed the rank of
M. Making fast algorithms that also output certificates is an active
area of research and would be a cool addition to Sage. (I wouldn't be
able to mentor such a project though: I don't know much about
certificates, and I will likely be mentoring another project).
Best,
Johan
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Re: [sage-devel] Re: I think my students hate me
On Tue, Mar 8, 2016 at 3:55 PM, kcrisman wrote: > I do have a basement but it's definitely not a place to do Sage, and in any > case have found trains to be an effective place to work on Sage, if the > wireless is working... Who needs wireless? I thought that was what git was good for ;) -- 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 post to this group, send email to sage-devel@googlegroups.com. Visit this group at https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
[sage-devel] Re: Query about SageMath for GSOC
On Tuesday, March 8, 2016 at 4:02:48 PM UTC+1, kcrisman wrote:
>
> sage: a,b = 2, 12
> sage: a,b = SR(a), SR(b)
> sage: a.add(b,hold=True)
> 14
>
> so I think this might be pretty hard unless one messed a lot with the
> internals (e.g. Pynac/Ginac).
>
Why not
sage: print '{0} + {1}'.format(a, b)
2 + 12
I mean, you *know somehow you need an add, so why not print it yourself?
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