[sage-devel] Re: integration algorithms

[parisse]

Le vendredi 3 mars 2017 23:20:42 UTC+1, rjf a écrit :
>
> If you were teaching calculus, at what point would you want
> your students to take out a smartphone and do integrals?
>
>
At least as soon as they are at level n+1 if integration is teached at 
level n. At level n, make 2 kinds of exam: one with CAS and one without.

How much time would you allocate to teaching the syntax
> of the CAS, what to do with error messages, how to download
> the latest copy,  etc.?
>

My own experience with Xcas on a desktop is that it takes less than 1h for 
1st year students to be able to do basic CAS stuff (simplify, derive, 
integrate, plot, etc.) and a little more with CAS calculators. Running Xcas 
on a smartphone is really straightforward, just open the URL 
, while installing 
it locally for an exam takes a few more steps (install an unarchive app, 
run it and locate the HTML5 page on the device).

 And what benefit would this be to
> the student who may still need to solve problems without
> a CAS for a written exam?
>

I believe that CAS devices should be allowed for exam except for short 
interrogations where you check very basic stuff. That could be calculators, 
or smartphone/tablets with some way to disconnect them from the network.


> Or do we assume that it is no longer necessary to teach
> methods of integration,  just as it is no longer necessary
> to teach how to compute square-roots, or how to
> interpolate in a table of logarithms.
>

It depends. Integration by part for example should be teached. Or 
integrating simple rational fractions (say denominators of degree 2). But I 
believe it is not required anymore to teach how to compute by hand higher 
degree fractions like 1/(x^2-1)/(x^2+x+1)^2, today it's more important to 
know how to do it with a CAS and how to check that you did not make a typo.


> Having taught a calculus + computer lab many years
> ago (1973! at MIT), the students were more interested
> in the Risch algorithm (simple version) than "regular"
> stuff.  Even today, calculus classes don't teach that, do they?
>
>
Of course no, and there is one good reason for that: most colleagues do not 
even know what the Risch algorithm is about.

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Re: [sage-devel] Hiding answers to non-trivial exercises in thematic tutorials

[Jori Mäntysalo]

On Fri, 3 Mar 2017, Thierry wrote:


that we should propose a solution or some hints. However, the solution
should not be readable at the first look of the page, but still accessible
by the user.


Did we already have a discussion about this? HTML manual could have for 
example ALGORITHM-part "hidden", and maybe some larger code snippets 
available behind a click and so on.


--
Jori Mäntysalo

[sage-devel] Re: integration algorithms

[John H Palmieri]

Calculus classes today do not typically teach the Risch algorithm, in my 
experience. However, you shouldn't design calculus courses at most places 
based on experiences with MIT students.

I think it is an interesting question about how much time we should spend 
teaching *how* to compute integrals vs. *when* to compute integrals. For 
the *how* question, how much by hand and how much by CAS?

But all of this is getting off-track, I think.

-- 
John


On Friday, March 3, 2017 at 2:20:42 PM UTC-8, rjf wrote:
>
> If you were teaching calculus, at what point would you want
> your students to take out a smartphone and do integrals?
>
> How much time would you allocate to teaching the syntax
> of the CAS, what to do with error messages, how to download
> the latest copy,  etc.?  And what benefit would this be to
> the student who may still need to solve problems without
> a CAS for a written exam?
>
> Or do we assume that it is no longer necessary to teach
> methods of integration,  just as it is no longer necessary
> to teach how to compute square-roots, or how to
> interpolate in a table of logarithms.
>
> Having taught a calculus + computer lab many years
> ago (1973! at MIT), the students were more interested
> in the Risch algorithm (simple version) than "regular"
> stuff.  Even today, calculus classes don't teach that, do they?
> RJF
>
> On Wednesday, March 1, 2017 at 11:51:34 PM UTC-8, parisse wrote:
>>
>>
>>
>> Le mercredi 1 mars 2017 22:58:48 UTC+1, rjf a écrit :
>>>
>>> As I have said before, the objective of most students taking calculus
>>> is to pass the course so they never have to know any of this integration
>>> stuff ever again.  Thus computer systems are useful primarily to
>>> help them do homework (cheat?).  And for this work, Maxima is probably
>>> sufficient.
>>>
>>>
>>> A reasonable CAS on a smartphone/tablet/calculator is sufficient for 
>> students learning calculus (at some point geogebra will certainly provide 
>> the CAS window on their app). Otherwise I believe that more symbolic 
>> integration is essentially interesting for benchmarks (beware that they may 
>> be biaised) and to make regression tests (compare output and check that the 
>> derivative of the antiderivative is the original function).
>>
>

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[sage-devel] Re: integration algorithms

[rjf]

If you were teaching calculus, at what point would you want
your students to take out a smartphone and do integrals?

How much time would you allocate to teaching the syntax
of the CAS, what to do with error messages, how to download
the latest copy,  etc.?  And what benefit would this be to
the student who may still need to solve problems without
a CAS for a written exam?

Or do we assume that it is no longer necessary to teach
methods of integration,  just as it is no longer necessary
to teach how to compute square-roots, or how to
interpolate in a table of logarithms.

Having taught a calculus + computer lab many years
ago (1973! at MIT), the students were more interested
in the Risch algorithm (simple version) than "regular"
stuff.  Even today, calculus classes don't teach that, do they?
RJF

On Wednesday, March 1, 2017 at 11:51:34 PM UTC-8, parisse wrote:
>
>
>
> Le mercredi 1 mars 2017 22:58:48 UTC+1, rjf a écrit :
>>
>> As I have said before, the objective of most students taking calculus
>> is to pass the course so they never have to know any of this integration
>> stuff ever again.  Thus computer systems are useful primarily to
>> help them do homework (cheat?).  And for this work, Maxima is probably
>> sufficient.
>>
>>
>> A reasonable CAS on a smartphone/tablet/calculator is sufficient for 
> students learning calculus (at some point geogebra will certainly provide 
> the CAS window on their app). Otherwise I believe that more symbolic 
> integration is essentially interesting for benchmarks (beware that they may 
> be biaised) and to make regression tests (compare output and check that the 
> derivative of the antiderivative is the original function).
>

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[sage-devel] Re: a 7(!) year old (Singular) overflow issue still holds

[Jakob Kroeker]

I asked in the Singular forum, how to change the exponent size for Singular:

https://www.singular.uni-kl.de/forum/viewtopic.php?f=10=2576

Is it transparent for overflow detection?
>

I don't understand the question.

My question is, does overflow detection work correcly with different 
exponent sizes than 16 bit?


Am Montag, 13. Februar 2017 21:40:03 UTC+1 schrieb Bill Hart:
>
> I can only answer one of your questions.
>
> On Saturday, 11 February 2017 17:16:29 UTC+1, Jakob Kroeker wrote:
>>
>> By default, Singular uses 16 bit exponents. But it is perfectly capable 
>>> of working with exponents up to 64 bits. That will be slower of course.
>>>
>>
>> How to change this? Is it runtime or compile-time?
>>
>
> I believe it can be set at runtime. Hans surely knows how to change it.
>  
>
>> Is it transparent for overflow detection?
>>
>
> I don't understand the question.
>  
>
>>
>> I guess it isn't easy for Sage to change the relevant ring upon overflow 
>>> to one using 64 bit exponents.
>>>
>>
>> I have no idea;
>>
>> Jakob
>>
>

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Re: [sage-devel] Re: The end of our current R saga ? Reviews needed.

[Jeroen Demeyer]

On 2017-03-03 15:27, Emmanuel Charpentier wrote:

This set of tickets is up for review again since about two weeks. in
Trac#21770 , Jeroen Demeyer is
of the opinion of keeping curl (and probably pcre, but he doesn't say
that) as optional packages "for a while". This woulkd delay our already
exceeding late upgrade of R by the same amount.


No, it would not delay anything since I proposed to make those packages 
standard exactly when we upgrade R to the version which needs those 
packages.


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Re: [sage-devel] Re: The end of our current R saga ? Reviews needed.

[Emmanuel Charpentier]

The time should be NOW, unless review exhibits some snags...

--
Emmanuel Charpentier


Le 3 mars 2017 17:04, "Jeroen Demeyer"  a écrit :

> On 2017-03-03 15:27, Emmanuel Charpentier wrote:
>
>> This set of tickets is up for review again since about two weeks. in
>> Trac#21770 , Jeroen Demeyer is
>> of the opinion of keeping curl (and probably pcre, but he doesn't say
>> that) as optional packages "for a while". This woulkd delay our already
>> exceeding late upgrade of R by the same amount.
>>
>
> No, it would not delay anything since I proposed to make those packages
> standard exactly when we upgrade R to the version which needs those
> packages.
>
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Re: [sage-devel] Re: How to provide answers to non-trivial exercises in thematic tutorials ?

[Thierry]

Hi,

On Fri, Mar 03, 2017 at 06:42:43AM -0800, Emmanuel Charpentier wrote:
> Dear Thierry,
> 
> If I understand you correctly, you'd like to see Sage documentation acting 
> a bit like courseware ?

No, i just want to be able to propose exercises with hints or solutions in
thematic tutorials.

> If so, I think that this is a bit peripheral to Sage *Documentation*
> needs, where our primary goal should be to *enhance* information
> availability, not hinder it.

Well,
- perhaps "hiding" was an ill-chosen word, let me replace it with
  "providing" in the topic of this thread,
- spoiling can contribute to hindering reflection,
- knowledge is not limited to information, understanding is not
  peripheral,
- Sage documentation does not have single goal, in particular, the
  reference manual and the thematic tutorials are different, and those
  latter might benefit from non-trivial exercises. And since they are
  supposed to be worked in autonomy, we have to provide solutions
  somewhere, while letting the possibility for the user to think first,
- if most text books propose exercises, whose hardest got hints or
  solutions at the end of the volume, i guess there are good reasons.

> However, it might be an interesting development for cloud.sagemath.com 
> (with another set of examples, obviously...).

A non-trivial part of the humanity does not have enough bandwidth to use
such online services, so it might be a good idea to provide the same
variety of documents within Sage documentation (note that most free Sage
books are already available as pdf in the Sage Debian Live, as well as all
the Sage documentation).

I am just trying to write a thematic tutorial, and i do not want to remove
some exercises, just because they go beyond an informational brain dump.

I dont get the point in reserving exercises "experiment this", "what do
you notice?", "could you explain the behaviour?", "how would you fix the
issue?",... to online platforms.
 
Ciao,
Thierry



> Sincerely,
> 
> --
> Emmanuel Charpentier
> 
> Le vendredi 3 mars 2017 13:23:04 UTC+1, Thierry (sage-googlesucks@xxx) a 
> écrit :
> >
> > Hi, 
> >
> > currently thematic tutorials are made of examples and straightforward 
> > application exercises. I would like to propose non-trivial exercises, so 
> > that we should propose a solution or some hints. However, the solution 
> > should not be readable at the first look of the page, but still accessible 
> > by the user. 
> >
> > I was thinking of: 
> >
> > - having some additional EXERCISE/QUESTION/SOLUTION/ANSWER/HINT sections 
> >   similar to EXAMPLES/TESTS, for which SOLUTION/ANSWER/HINT are folded by 
> >   default. 
> >
> > - having a HIDDEN_TOPIC sphinx directive similar to TOPIC which leads to a 
> >   folded block by default (TOPIC directive is used for exercises e.g. in 
> >   
> > http://doc.sagemath.org/html/en/thematic_tutorials/tutorial-comprehensions.html)
> >  
> >
> >
> > - putting solutions in a separate file and make links to it (through it 
> >   links might be a bit fastidious to maintain). I currently do this for my 
> >   tutorials (basically i write a worksheet with solutions, and when it is 
> >   ready, i remove the solutions and produce a second worksheet). 
> >
> > - you might have your own workflow for such a situations, which i am 
> >   interested in. 
> >
> > It would be wonderful if this could work with sphinx (online doc) as well 
> > as in ipynb (obtained with "sage -rst2ipynb" command) for indepentent 
> > jupyter worksheets to be distributed to students. 
> >
> > I opened https://trac.sagemath.org/ticket/22508 for that, but i am 
> > clearly 
> > incompetent and do not see any way to achieve that. So, any help or 
> > suggestion would be very welcome ! 
> >
> > Ciao, 
> > Thierry 
> >
> >
> 
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Re: [sage-devel] "replacement" optional packages

[Erik Bray]

On Wed, Mar 1, 2017 at 8:52 AM, Jeroen Demeyer  wrote:
> I have been thinking about this too. My personal conclusion was that the
> "type" enumeration (standard, optional, experimental, pip, script) is simply
> too restricted and that we need additional metadata with more degrees of
> freedom.
>
> Currently, the "type" field is relevant for:
> - which packages are installed by default
> - which packages should be packed in the source tarball
> - which --optional tags are given when doctesting
> - whether a warning message is given when installing the package
> - the Make rules of a package
> - the automatic dependencies of a package
>
> I think that's bordering on being too much already. So +1 to more metadata
> but -1 to inventing yet another type.

Agreed.  What we want here is "provides".  For example:

"provides: blas"

where "blas" is an abstract dependency which may be fulfilled by
multiple packages (more or less like we already do, but more
concretely).

In Debian the alternatives [1] system is used to manage what concrete
package is being used to provide an abstract dependency.

Coincidentally I posted #22509 [2], which might be useful for this, a
little before reading this thread.  My motivation there was to support
uninstallation better.  But another case for it could be managing
package alternatives in such a way that obviates needing to rebuild
every one switches packages.  For example, one could have builds of
both openblas and atlas living in directories outside $SAGE_LOCAL (but
that are *not* temporary as my ticket suggests).  Then one could use a
modified form of the uninstall procedure described in #22510 [3] to
swap one package out for the other.

[1] https://wiki.debian.org/DebianAlternatives
[2] https://trac.sagemath.org/ticket/22509
[3] https://trac.sagemath.org/ticket/22510

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[sage-devel] Re: Hiding answers to non-trivial exercises in thematic tutorials

[Emmanuel Charpentier]

Dear Thierry,

If I understand you correctly, you'd like to see Sage documentation acting 
a bit like courseware ?

If so, I think that this is a bit peripheral to Sage *Documentation* needs, 
where our primary goal should be to *enhance* information availability, not 
hinder it.

However, it might be an interesting development for cloud.sagemath.com 
(with another set of examples, obviously...).

Sincerely,

--
Emmanuel Charpentier

Le vendredi 3 mars 2017 13:23:04 UTC+1, Thierry (sage-googlesucks@xxx) a 
écrit :
>
> Hi, 
>
> currently thematic tutorials are made of examples and straightforward 
> application exercises. I would like to propose non-trivial exercises, so 
> that we should propose a solution or some hints. However, the solution 
> should not be readable at the first look of the page, but still accessible 
> by the user. 
>
> I was thinking of: 
>
> - having some additional EXERCISE/QUESTION/SOLUTION/ANSWER/HINT sections 
>   similar to EXAMPLES/TESTS, for which SOLUTION/ANSWER/HINT are folded by 
>   default. 
>
> - having a HIDDEN_TOPIC sphinx directive similar to TOPIC which leads to a 
>   folded block by default (TOPIC directive is used for exercises e.g. in 
>   
> http://doc.sagemath.org/html/en/thematic_tutorials/tutorial-comprehensions.html)
>  
>
>
> - putting solutions in a separate file and make links to it (through it 
>   links might be a bit fastidious to maintain). I currently do this for my 
>   tutorials (basically i write a worksheet with solutions, and when it is 
>   ready, i remove the solutions and produce a second worksheet). 
>
> - you might have your own workflow for such a situations, which i am 
>   interested in. 
>
> It would be wonderful if this could work with sphinx (online doc) as well 
> as in ipynb (obtained with "sage -rst2ipynb" command) for indepentent 
> jupyter worksheets to be distributed to students. 
>
> I opened https://trac.sagemath.org/ticket/22508 for that, but i am 
> clearly 
> incompetent and do not see any way to achieve that. So, any help or 
> suggestion would be very welcome ! 
>
> Ciao, 
> Thierry 
>
>

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[sage-devel] Re: The end of our current R saga ? Reviews needed.

[Emmanuel Charpentier]

This set of tickets is up for review again since about two weeks. in 
Trac#21770 , Jeroen Demeyer is of 
the opinion of keeping curl (and probably pcre, but he doesn't say that) as 
optional packages "for a while". This woulkd delay our already exceeding 
late upgrade of R by the same amount.

I am of the opinion that this upgrade is urgently needed (we are almost on 
year behind R), and I wouldn't like to see Sagematrh 7.6 getting out 
without it, or a good reason not to include it. I have ran it on my 
ptrivate branch for about 8 months, with no noticeable problems ; the 
delays were induced by the necessity of depending on an external SSL 
library (done since Trac#22189 

).

Questions :
What is your opinion ?
Should we hold a formal vote ?
Can you review this set of packages (I think that the two most important 
cases are Mac and Cygwin, both aving peculiarities) ?

Sincerely (and expectantly),

--
Emmanuel Charpentier


Le dimanche 19 février 2017 06:21:26 UTC+1, Emmanuel Charpentier a écrit :
>
> Dear list,
>
> We are about one year behind current R (Sagemath Cloud even installed a 
> "modern" R Jupyter kernel as an alternative to "our" R for Jupyter 
> purposes). To solve this, three patches need your attention :
>
> Sage-7.6.beta4 + Trac#20523  
> (upgrade R to 3.3.2) + Trac#21767  
> (add curl as new standard package) + Trac#21770 
>  (add pcre as new standard 
> package) passes ptestlong with two transient errors :
> --
> sage -t --long src/sage/homology/simplicial_set_morphism.py  # Bad exit: 2
> sage -t --long src/sage/homology/simplicial_complex.py  # 1 doctest failed
> --
> Both tests pass when run standalone.
>
> Reminder : since Trac#22189 , we 
> ***depend*** on some SSL system-wide library, and we strongly recommend 
> OpenSSL. This is true also for patchbots ;-).
>
> This should close the R saga (for now) by allowing the current interfaces 
> to work with R >= 3.3.x.
> For docudrama lovers, the next cliffhanger should be a future Rpy2-based R 
> interface ;-). But don't hold your breath...
>
> HTH,
>
> --
> Emmanuel Charpentier
>
>

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[sage-devel] Hiding answers to non-trivial exercises in thematic tutorials

[Thierry]

Hi,

currently thematic tutorials are made of examples and straightforward
application exercises. I would like to propose non-trivial exercises, so
that we should propose a solution or some hints. However, the solution
should not be readable at the first look of the page, but still accessible
by the user. 

I was thinking of:

- having some additional EXERCISE/QUESTION/SOLUTION/ANSWER/HINT sections
  similar to EXAMPLES/TESTS, for which SOLUTION/ANSWER/HINT are folded by
  default.

- having a HIDDEN_TOPIC sphinx directive similar to TOPIC which leads to a
  folded block by default (TOPIC directive is used for exercises e.g. in
  
http://doc.sagemath.org/html/en/thematic_tutorials/tutorial-comprehensions.html)

- putting solutions in a separate file and make links to it (through it
  links might be a bit fastidious to maintain). I currently do this for my
  tutorials (basically i write a worksheet with solutions, and when it is
  ready, i remove the solutions and produce a second worksheet).

- you might have your own workflow for such a situations, which i am
  interested in.

It would be wonderful if this could work with sphinx (online doc) as well
as in ipynb (obtained with "sage -rst2ipynb" command) for indepentent
jupyter worksheets to be distributed to students.

I opened https://trac.sagemath.org/ticket/22508 for that, but i am clearly
incompetent and do not see any way to achieve that. So, any help or
suggestion would be very welcome !

Ciao,
Thierry

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