[sage-edu] Re: Why SAGE as opposed to, say, SCILAB?

2008-06-06 Thread Robert Bradshaw

I am sure other people will have more to say about this, but SCILAB  
seems to be more aimed at numerical computation and doesn't have much  
support for working in areas like number theory, combinatorics, exact  
linear algebra, etc. There's also a question of licensing (more  
restrictive commercial use) though I see there are plans to change that.

- Robert


On Jun 6, 2008, at 4:26 PM, miner_tom wrote:

>
> Hi,
>
> Last night I became aware of SAGE through a televised lecture by the
> developer. I am familiar with different mathematical software, and one
> of the key reasons that the developer gave for all of the effort that
> he put into developing SAGE was that there was no open source
> mathematical software "out there" that would do the job.
>
> I was wondering, since SCILAB is open source, why was SCILAB not
> satisfactory?
>
> Thank You
> Tom
> [EMAIL PROTECTED]
>
>
> >


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[sage-edu] Re: material for sage screencast

2008-09-16 Thread Robert Bradshaw

On Sep 16, 2008, at 10:42 AM, Jose wrote:

>
> All:
>
> I'm thinking about putting together another screencast in the same
> vein as
>
> http://showmedo.com/videos/video?name=2450010&fromSeriesID=245
>
> on the special idioms in sage (i.e. the 0..10 = range(10)) and on the
> new functions to put GUI components on variables in the notebook
> interface.

I think this is a great idea. Note, however, that range(10) is 1..9  
as in Python the upper endpoint is not included.

- Robert



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[sage-edu] Re: material for sage screencast

2008-09-16 Thread Robert Bradshaw

On Sep 16, 2008, at 1:25 PM, [EMAIL PROTECTED] wrote:

> William Stein wrote:
>> On Tue, Sep 16, 2008 at 1:10 PM, Jose <[EMAIL PROTECTED]> wrote:
>>
>>> Sorry for the confusion  regarding range().
>>>
>>> Are there other idioms not in standard python that should be
>>> highlighted?
>>>
>>> Thanks!
>>>
>>
>>
>
> I'll take a shot at brief explanations for the archive's sake.
>
>
>> sage: 1/3
>> 1/3# instead of 0
>>
>>
>
> Sage makes rational numbers, while Python does integer division.
>
>
>> sage: 1/3.0
>> 0.333
>>
>> but in Python:
>>
> 1/3.0
>
>> 0.1
>>
>>
>
> Sage uses more precise arithmetic?

Sage avoid showing the last couple of bits to hide numerical noise.  
It also uses MPFR by default.

>
>
>>
>> sage: 1.290283409823049820938409283409823408234
>> 1.290283409823049820938409283409823408234
>>
>> but in python
>>
>>
> 1.290283409823049820938409283409823408234
>
>> 1.2902834098230498
>>
>
> Sage uses arbitrary precision floats by default, while Python only  
> uses
> double precision.  (Is it really arbitrary precision?  I think it is.)

Sage uses fixed precision floating point numbers, with the precision  
determined by the number of digits in the input.

- Robert


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[sage-edu] Re: class grade book in Sage?

2008-10-22 Thread Robert Bradshaw

On Oct 22, 2008, at 5:58 AM, kcrisman wrote:

>>> Of course, because I like Sage I'd like to be able to do this
>>> entirely in Sage. One problem with gnumeric is that
>>> there is no mac version I know of. (Of course,
>>> one could buy excel for a mac but I don't want to do that.)
>
> You can use it (and I do, rarely) on Mac with X11 installed.  I
> routinely use Xfig this way to create diagrams for class on my Mac.

One can use OpenOffice on the Mac as well (or a more native port,  
like NeoOffice).

>
>>
>>> For example, I know nothing about moodle. Does anyone know
>>> if moodle can be used for this?
>
> I believe so, since it aims to do the same things as e.g. Blackboard
> and quite major universities which have to comply with FERPA use it.
> I wouldn't be surprised if there were some Moodle adopters at the JMM
> who come to one of the Sage-related sessions; you might want to ask on
> one of their forums about this sort of thing.  Sakai is another open-
> source Course Management Software package with a wide user base.  At
> least one of them should support some sort of scripting, or perhaps
> have code which could be integrated, but I can't say more than that.

I think something like this would be better accomplished by some sort  
of integration with Sage and, e.g. Moodle or Blackboard that are made  
for this kind of things, rather than trying to include/roll our own  
system.

- Robert




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[sage-edu] Re: www.sagenb.org

2009-01-15 Thread Robert Bradshaw

On Jan 15, 2009, at 4:10 PM, calcp...@aol.com wrote:

> That's interesting because I calculated M37 = 2^3021377-1 (909526  
> digits) on a 2.6 GHz pentium 4 using my own C++ class to represent  
> large ints and it about 2 hours.
>
> I calculated the same thing on www.sagenb.org and it took about 6  
> minutes!

Yeah, sagenb.org can get pretty loaded down some times. This is on my  
laptop (2.33 GHz Intel Core 2 Duo)

sage: time M37 = 2^3021377-1
CPU times: user 0.00 s, sys: 0.00 s, total: 0.00 s
Wall time: 0.00 s
sage: time len(str(M37))
CPU times: user 1.06 s, sys: 0.03 s, total: 1.08 s
Wall time: 1.09 s
909526

Note that the bulk of the time is spent getting the (decimal) string  
representation of M37. Of course, if I only wanted the number of  
digits, I could more quickly do

sage: time RIF(M37).log(10)
CPU times: user 0.00 s, sys: 0.00 s, total: 0.00 s
Wall time: 0.00 s
909525.1052092525?

I wonder if doing this via the notebook took so long because of the  
overhead of sending the data back (most browsers don't do well with  
nearly a MB of text in a cell...). Sage uses gmp in the background to  
do it's big integer arithmetic and is both very tightly coded and has  
a wide range of asymptotically fast algorithms, which shouldn't  
impact this case, but for another example:

sage: time a = M37^2
CPU times: user 0.09 s, sys: 0.01 s, total: 0.10 s
Wall time: 0.10 s

> Well, I suppose 4 Xeon cores is a mini cluster of sorts.

Yeah, it's not bad for a desktop :).

- Robert


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[sage-edu] Re: www.sagenb.org

2009-01-15 Thread Robert Bradshaw

On Jan 15, 2009, at 4:25 PM, calcp...@aol.com wrote:

> OK, I'm confused about the time procedure.  What's the difference  
> between
> sage: time s =  2^3021377-1
> CPU time: 0.00 s,  Wall time: 0.00 s

The variable s now holds the integer 2^3021377-1, represented  
internally in binary.

> and
> sage: time k = str(s)
> CPU time: 0.67 s,  Wall time: 0.67 s

k now holds the string (decimal) representation of s, as a python  
string object (essentially a char* under the hood). This is much  
harder to compute (the internal format is not decimal), and took  
nearly a second on his machine.

If I were to write

sage: 2^3021377-1

it would first compute the value, then turn it into a string for  
printing. The above separates the two steps. Hope that helps clarify  
things.

- Robert


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[sage-edu] Re: www.sagenb.org

2009-01-15 Thread Robert Bradshaw

On Jan 15, 2009, at 4:39 PM, William Stein wrote:

> On Thu, Jan 15, 2009 at 4:21 PM, Robert Bradshaw
>  wrote:
>>
>> On Jan 15, 2009, at 4:10 PM, calcp...@aol.com wrote:
>>
>>> That's interesting because I calculated M37 = 2^3021377-1 (909526
>>> digits) on a 2.6 GHz pentium 4 using my own C++ class to represent
>>> large ints and it about 2 hours.
>>>
>>> I calculated the same thing on www.sagenb.org and it took about 6
>>> minutes!
>>
>> Yeah, sagenb.org can get pretty loaded down some times.
>
> He was saying that "6 minutes" was very very fast, not slow.

I was comparing it to what times I would have expected to see based  
on my local timings. The online notebook sometimes felt sluggish to  
me, but I do almost everything locally so it's not a fair comparison  
(and I only occasionally use it, probably less than a dozen times  
since we moved it off the old hardware).

> [[his
> timing turns
> out to really have been of printing out the answer via the notebook.
> better would be to do
> sage: time s =  2^3021377-1
> CPU time: 0.00 s,  Wall time: 0.00 s
> sage: time open('output.txt','w').write(str(s))
> CPU time: 0.70 s,  Wall time: 0.70 s
>
> which gives a link to a file that you can download that contains  
> the answer.]]

Yep, that was my diagnosis of the 6 minutes too. Or perhaps as  
mentioned it was a different Mersenne prime that we're talking about,  
but in any case it's a big answer to try and display in a browser.

- Robert


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[sage-edu] Re: www.sagenb.org

2009-01-15 Thread Robert Bradshaw


On Jan 15, 2009, at 4:53 PM, William Stein wrote:

>>> [[his
>>> timing turns
>>> out to really have been of printing out the answer via the notebook.
>>> better would be to do
>>> sage: time s =  2^3021377-1
>>> CPU time: 0.00 s,  Wall time: 0.00 s
>>> sage: time open('output.txt','w').write(str(s))
>>> CPU time: 0.70 s,  Wall time: 0.70 s
>>>
>>> which gives a link to a file that you can download that contains
>>> the answer.]]
>>
>> Yep, that was my diagnosis of the 6 minutes too. Or perhaps as
>> mentioned it was a different Mersenne prime that we're talking about,
>
> It wasn't.  2^3021377-1 is the third largest known and the next two  
> larger are
> only slightly bigger.

Good point. Even the latest ones found shouldn't take much longer to  
compute the decimal representation of (certainly not minutes).

- Robert



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[sage-edu] Re: www.sagenb.org

2009-01-15 Thread Robert Bradshaw

On Jan 15, 2009, at 4:57 PM, calcp...@aol.com wrote:

> In a message dated 1/15/2009 7:53:24 P.M. Eastern Standard Time,  
> wst...@gmail.com writes:
> It wasn't.  2^3021377-1 is the third largest known and the next two  
> larger are
> only slightly bigger.
> I was calculating M37 which is the largest known Mersenne less than  
> 10^6 digits long.
>
> www.mersenne.org (GIMPS) is up to M46 which is over 12*10^6 digits  
> long!

Even then

sage: n = 43112609
sage: time m = (2^n - 1)
CPU times: user 0.01 s, sys: 0.01 s, total: 0.02 s
Wall time: 0.02 s
sage: time s = str(m)
CPU times: user 37.57 s, sys: 1.41 s, total: 38.98 s
Wall time: 39.40 s
sage: len(s)
12978189

Of course, these latest Mersenne primes aren't known to have been  
discovered in order.

- Robert


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[sage-edu] Re: www.sagenb.org

2009-01-17 Thread Robert Bradshaw

On Jan 17, 2009, at 5:51 AM, calcp...@aol.com wrote:

> BTW, if www.sagenb.org runs on a single PC with a quadcore, the
> question still remains, is Sage multicore aware without dSage or are
> you using dSage here?

Some of the underlaying components, like ATLAS, can be compiled to be  
multicore aware, but for the most part one uses DSage or pyprocessing  
to take advantage of this. There have been several threads on this in  
sage-devel and sage-support. The notebook itself, however, starts a  
separate sage instance per worksheet, so it can easily take advantage  
of multiple cores. I think the VMWare player only will give you two  
cores, no matter how many physical cores it has.

- Robert


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[sage-edu] Re: sage mailing lists

2009-01-27 Thread Robert Bradshaw

On Jan 27, 2009, at 3:12 PM, calcp...@aol.com wrote:

> In a message dated 1/27/2009 2:38:49 A.M. Eastern Standard Time,  
> wst...@gmail.com writes:
> This discussion should be on sage-nt, the list for sage number theory
> discussion:
> Oh, I did not know of this list!  How do I get a list of all sage  
> forums?  I only know of sage-edu, sage-support and sage-devel!  Now  
> there's sage-nt too?
>

There's sage-combinat, sage-announce, and sage-trac (to be notified  
of every ticket change). I'm not sure of any others, but it would be  
good to have a list somewhere on the site. The goal of more specific  
lists is because the volume of traffic on sage-devel and sage-support  
is just too high for some people.

- Robert



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[sage-edu] Re: NSF report on math - tech part

2009-02-17 Thread Robert Bradshaw

On Feb 13, 2009, at 8:43 AM, jason-s...@creativetrax.com wrote:

> kcrisman wrote:
>> The NSF has just put out a video series (five minutes each, maybe) on
>> the state of math ed in the country.  It's actually somewhat
>> disappointingly vague in parts, but certainly has potential to get
>> people talking.
>>
>> Relevance to Sage:
>> http://www.nsf.gov/news/special_reports/math/tech.jsp
>> This subsegment talks a lot about things like interactive notebooks
>> and textbooks, which is certainly related to a lot of the Sage/TeX/ 
>> pdf
>> interactions that have been discussed.  Some of you might find it
>> interesting to see what the talking heads here have to say about all
>> this.
>>
>
> Thanks for posting this.  These are very interesting short clips.
>
>
>
>> If Sage could easily be integrated with tablet technology, for
>> instance (e.g. character recognition and then knowing how to  
>> translate
>> that into Sage commands) that could be very interesting 10 years down
>> the road, or whenever we all stop typing.  If we do!
>
> I doubt we will stop typing in general for a very long time, if ever.
> Nothing even comes close to the precision and speed that typing  
> usually
> affords.  That said, I was *really* impressed with a tablet PC running
> Vista that I played with the other day.  I was amazed at the  
> handwriting
> recognition and one-note---things have certainly come a long way in  
> the
> last few years.  I didn't test its ability to recognize math, though.

I don't think typing will go away anytime soon either, but my first  
thought is that a tablet could be really good for imputing math  
formula, commutative diagrams, etc. TeX does a pretty good job of  
linearizing it, but even after one is fluent it's nowhere near as  
natural as chalk on a whiteboard or pen and paper.

- Robert



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[sage-edu] Re: sage-moodle integration

2009-02-17 Thread Robert Bradshaw

On Feb 15, 2009, at 6:23 AM, mabshoff wrote:

> On Feb 15, 6:17 am, David Joyner  wrote:
>
> Hi,
>
>> Hi Herli. There are people working on this, but off the top of my  
>> head
>> I am not sure if they are members of this list or not. If no one  
>> replies
>> within several days, I'll dig up emails and try to get your  
>> question to the
>> right people or else send you their addresses. You might also  
>> search sage-edu
>> and sage-support archives for "moodle".
>
> Mike Hansen has played with this and he is a member of this group, so
> once he is back up you can expect an answer by him. Overall we would
> very much welcome an integration with MOODLE, but so far no one has
> actually submitted a patch to do so. Maybe you can describe what needs
> to be done in that direction or point us to some links/documentation
> from the end of MOODLE in case you are familiar with it.

I actually wrote the whole http API with Moodle in mind. However, I  
don't know the Moodle framework or source (or time to learn it yet)  
so didn't take it any further. If there's someone out there who knows  
Moodle I would be very happy to work with them for a Moodle-sage  
plugin, as I know the Sage side fairly well.

- Robert


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[sage-edu] Re: 3d tubes in SAGE

2009-05-07 Thread Robert Bradshaw

On May 7, 2009, at 12:29 AM, Rado wrote:

> Hello,
>
> To test the 3D plotting abilities of sage, I tried to implement some
> basic tube plotting like the ones here
> http://facstaff.unca.edu/mcmcclur/java/LiveMathematica/tubes.html
> (mathematica handles those beautifully).
>
> The code is nice and short and I think the pretty picture that comes
> out is good for SAGE posters or the show-off page in the wiki. To
> compete with mathematica all that's left is putting nicer color
> textures, but I don't know how to do that with JMOL.
>
> #Original idea: http://facstaff.unca.edu/mcmcclur/java/ 
> LiveMathematica/tubes.html
> #SAGE translation: Radoslav Kirov
>
> def vector_normalize(v):
> return v/sqrt(v*v)
>
> x,s = var('x,s')
> curve = vector([sin(x), cos(x),0])
> #if you are happy with the torus, try the trefoil knot
> #curve = vector([sin(3*x), sin(x)+2*sin(2*x), cos(x)-2*cos(2*x)])
> tangent = diff(curve,x)
> unit_tangent = vector_normalize(tangent)
> normal = diff(unit_tangent,x)
> #alternative is to cross_product with a random vector. This might be
> faster but will make picture uglier.
> #you will probably, need to check that the tangent is not parallel to
> [1,1,1].
> #test_vector = vector([1,1,1])
> #normal = (test_vector.cross_product(unit_tangent))
> unit_normal = vector_normalize(normal)
> unit_binormal = unit_normal.cross_product(unit_tangent)
> radius = 0.3
> parametric_plot3d(list(curve + radius * cos(s) * unit_normal + radius
> * sin(s) * unit_binormal), (x,0,2*pi),(s,0,2*pi),aspect_ratio=[1,1,1])

Cool.

> Also, a warning for people who come from the world of Mathematica:
>
> sage: v=Vector([2,1])
> sage: v.normalize()
> (1, 1/2)
>
> I lost a good 15 min. on that. I am guessing this definition of
> normalize comes from polynomials but its quite weird for regular
> vector calculus.

Either that or gaussian elimination, but I find that definition  
strange as well...

- Robert



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[sage-edu] Re: interactive visualizing cross-sections of solids ?

2009-05-15 Thread Robert Bradshaw

I don't believe we have anything like this yet, but it seems it could  
be (relatively) easily built on top of the new and very cool 3d  
implicit plotting functionality.

- Robert

On May 15, 2009, at 1:42 AM, Jurgis Pralgauskis wrote:

>
> Hello,
>
> stereometry needs imagination or more experience,
> to understand cross-sections and so on
>
> I found some interactive example
> http://www.learner.org/courses/learningmath/geometry/session9/ 
> part_c/index.html
>
> I'd like to have sage interact for solid construction and
> cutting_plane parameters
> and then view it around via jmol :)
>
> in school this is  mostly needed for parallelepiped or pyramid solids:
>
> mysolid = SomeSolid(apex_points_3D)
> # and I can get, mysolid.surface_planes()
> #so I'd expect to have algorithms which detect
>
> intersection = Intersection(mysolid, cutting_plane)
> # we get some 2D polygon,
> # probably first analytically findintersection.lines
> # and then  solve the
> # self.segmets = self.endpoints (self.lines , self.mysolid)
> # for conic would be some different approach ...
>
> intersection.fill() # or draw() would draw some lines or color to  
> show it
>
>
> what does sage have already, and what would need to be hacked?
>
> Thanks in advance :)
>
> ps.: just for reference
> http://en.wikipedia.org/wiki/Cross_section_(geometry)
> http://en.wikipedia.org/wiki/Conic_section
>
> -- 
> Jurgis Pralgauskis
> Don't worry, be happy and make things better ;)
>
> >


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[sage-edu] Re: Multiplying lists

2009-07-22 Thread Robert Bradshaw

On Jul 21, 2009, at 4:52 PM, David Joyner wrote:

>
> On Tue, Jul 21, 2009 at 6:56 PM, Mike wrote:
>>
>> Hi, I have a quick question. I'm fairly new to python and sage,  
>> and am
>> attempting to learn it to use in my engineering classes. My  
>> problem is
>> that I have 2 lists
>> x = [1, 2, 3]
>> y = [4, 5, 6]
>> and I would like to use them both in the same function to give me a
>> third list. Something to the effect of:
>> z = [4^1, 5^2, 6^3] = [4, 25, 216]
>
>
> Is
>
> sage: x = [1, 2, 3]
> sage: y = [4, 5, 6]
> sage: z = [y[i]^x[i] for i in range(3)]; z
> [4, 25, 216]
>
>
> what you want?

Or even

sage: [a^b for a,b in zip(y,x)]
[4, 25, 216]

- Robert

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[sage-edu] Re: grant proposal season

2009-08-25 Thread Robert Bradshaw

On Aug 25, 2009, at 10:18 PM, Thierry Dumont wrote:

> jason-s...@creativetrax.com a écrit :
>>
>> Williams post:
>>
>> Hello,
>>
>> Grant proposal season is upon us, and things are in the works.
>> Imagine somebody said to you:
>>
>> "Please send me a list of items you would like us to fund.  What I
>> need is just a sentence or two (at most a
>> paragraph) describing the work ... and a ballpark estimate of the  
>> cost."
>>
>> Feel free to post in this thread any wishlist ideas along these lines
>> that you might have.  They could make there way into a proposal that
>> might get funded, and Sage development would consequently benefit
>> greatly.
>>
>> Thanks!
>>
>> William
>>
>
> 1) Sage Notebook (but this seems already in the development pipe- 
> line):
> -security and confidentiality: have true users, groups of users or
> something like that, who can share or *cannot* share worksheets. The
> possibility to protect worksheets is mandatory for examinations,  
> but non
> only for examinations.
>
> 2) Code generator(s): Maple is often used by engineers to generate  
> C (or
> Fortran) code. For example, if you develop finite element methods, you
> can have up to 128 polynomials to integrate on a simplex (this is only
> an example). Ok all this is trivial mathematics, but tedious. Maple
> makes the code for you: I know groups who buy Maple only for this  
> feature!

fast_callable already does this in a limited sense (it makes bytecode  
interpreters, not expression code itself) but the infrastructure is  
all sitting there to be able to do this.

- Robert



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[sage-edu] Re: SageIDE as an education-oriented GUI for Sage

2009-10-21 Thread Robert Bradshaw


On Oct 21, 2009, at 5:12 PM, Offray Vladimir Luna Cárdenas wrote:

>
> Hi,
>
> Thanks for your answers. I think also that starting simple and small  
> is
> a way to increase the use of Sage also. My questions about interface  
> and
> language because I'm trying to use CAS in education with notebooks  
> with
> a textual oriented interface instead of notebooks with a calculation
> oriented one. This is because I want to emphasize problem solving  
> using
> the heuristics of George Polya, so textual description of the students
> interpretation of the problem is more important that calculations. In
> this regard the notebook web interface has some issues and the
> integration of tinyMCE is a good step on user friendliness  but  
> there is
> a escape of the WYSIWYG metaphor to LaTeX code when there is a need to
> write math (and of course in a problem solving oriented math course is
> supposed to pass a lot). A work around that I'm using is the TeXmacs
> interface for Sage, but then I lose all the nice collaborative and
> ubiquitous features of the sage web interface. Having a nice equation
> editor integrated with tinyMCE (may be made in something similar to
> 280slides) would be a good step towards a textual oriented  
> interface. Of
> course you're thinking supercalculator integrated in a small form  
> factor
> laptop, but also you're thinking about filling the gaps so knowing  
> your
> thoughts about the gap between textual oriented and calculation  
> oriented
> interface would be a nice thing, even if this is not planed for  
> mathrider.

Note that it would be (relatively) easy to take the sage notebook and  
make it evaluate cells via a custom, simpler, interpreter
(that could call Sage underneath).

- Robert
  
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Re: [sage-edu] *Independently* doing Sage notebooks doesn't seem to work in high school...

2009-12-10 Thread Robert Bradshaw
On Dec 9, 2009, at 12:44 PM, michel paul wrote:

> > Sound familiar to anyone?
>
> Absolutely!  Yeah, the average HS student just wants to be told what  
> to do.  So this has been very tricky - how to get the kids to use  
> something like Sage/Python as a way to explore ideas on their own  
> when all they really want is to be told exactly what steps to follow  
> to guarantee an A.

I'll second this. Unfortunately the same goes for many college freshmen.

Another point that hasn't been brought up yet is that students don't  
usually expect to have to ask questions. Since many expect to be told  
everything, they often feel it's a sign of "stupidity" to not be able  
to execute. When I'd give out worksheets and say "if you have any  
questions, feel free to ask" I usually wouldn't get that much of a  
response, but walking around the class as they worked asking them  
about what they were doing would get them thinking and asking.

Another idea, since students just want to be told what to do (though  
it's a bit silly), is making asking at least one question a requirement.

- Robert

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Re: [sage-edu] Re: hardware/software requirements for a local Sage server

2009-12-11 Thread Robert Bradshaw
On Dec 11, 2009, at 9:52 PM, jason-s...@creativetrax.com wrote:

> Byungchul Cha wrote:
>> This discussion is very relevant to me, as I am also in the process  
>> of
>> working with our IT people at my campus in order to set up a sage
>> server for my college.
>>
>> My IT person suggests that I run a sage server in a virtual machine.
>> Are there any helpful tips in installing a sage server in a virtual
>> machine?
>
> The "Windows" download *is* Sage installed in a virtual machine.   
> Would
> that do?  All you have to do is download the Virtualbox image and  
> run it
> from Virtualbox.

It should be noted that this same Virtualbox image works fine for non- 
windows systems as well, and the public sage notebook server  
sagenb.org is served from within a virtual machine as well. So yes, it  
can and is being done.

- Robert

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Re: [sage-edu] Re: Calculus and Sage

2010-02-15 Thread Robert Bradshaw

On Feb 15, 2010, at 5:40 AM, kcrisman wrote:


Although I personally enjoy the *good* examples; honestly, I think it
would be irresponsible to ask someone taking calculus as a pre-
physical-therapy student (which ours are required to, for good
biomechanical reasons) to learn from a definition-theorem book.  This
student needs to understand force/time curves, possibly dosing things,
and the concepts of calculus; a physics student needs that but also
tons of practical computation techniques, the math major needs at
least some proofs, the econ major needs marginal cost and
complementary commodities... and then marketing decisions are made to
try to sell one book for *all* these constituencies.


I agree--as much as I like the definition-theorem format too, there is  
a definite bias in learning styles in this community ;). In my  
experience, math majors, let alone potential graduate students, are a  
small minority in Calculus classes (and most of those who would eat up  
a more rigorous approach will have probably tested out of first-year  
calculus anyways).


Despite that, $200+ 1200 page textbooks are overkill, and once free  
alternatives start becoming popular they'll have trouble justifying it.


- Robert

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Re: [sage-edu] Re: SAGE in abstract algebra class

2010-03-08 Thread Robert Bradshaw

On Mar 8, 2010, at 8:43 PM, Rob Beezer wrote:


Hi Mike,

First, thanks for your work on this.

An implementation of finite abelian groups would be at the top of my
list.  Folklore has it many have tried - not sure just where it gets
hard.


Implementing it isn't that hard (I think)--we already have a good  
implementation of free modules over Z (with quotients, homomorphisms,  
etc.) The "hard" part is swapping out the clean(er) implementation for  
what's there now. The abelian groups stuff was written ages ago,  
before there were any standards for anything, and lots of stuff uses  
it in odd ways and depends on its quarks, internal representations, etc.


- Robert


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Re: [sage-edu] Nicely written tutorial worksheets

2010-04-24 Thread Robert Bradshaw

On Apr 22, 2010, at 5:30 AM, Dan Drake wrote:


On Wed, 21 Apr 2010 at 10:53PM -0700, William Stein wrote:

A related idea -- when people click "public" they could opt-in with a
checkbox to publish under a certain license.  Then we can legally
collect together the best published worksheets elsewhere.


That's a great idea.


Explicit licensing would be great. It looks like we can use a
rel="license" attribute to make it both computer- and human-readable:

http://wiki.creativecommons.org/RelLicense


+1

- Robert

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Re: [sage-edu] Re: Long Island MAth CONference (LIMACON 2010 at SUNY Old Westbury)

2010-05-18 Thread Robert Bradshaw

On May 18, 2010, at 4:24 PM, A. Jorge Garcia wrote:


Wow, I tried using http://www.sagenb.org all day in class today and it
was WAY SLOW!!!

I finally discovered an alternate sage server at clemson and things
went a bit better.  I have tried the KAIST server inthe past, but it
seems to be down or not accepting new accounts.

What other servers are out there?


For reliable service, I would recommend setting up your own--if you're  
not giving sage accounts to other people it's as simple as typing


sage: notebook()

Of course the Sage notebook should scale better than it should, but  
until someone has time to look into that who knows how many thousands  
of people you're competing with resources for.


- Robert

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Re: [sage-edu] Trying to build a SageServer for my calculus class: A SageServer Vbox appliance?

2010-06-21 Thread Robert Bradshaw

On Jun 17, 2010, at 5:06 PM, Calcpage wrote:


Why set up a virtual box when you have linux?


For security reasons.



Regards,
A. Jorge Garcia
Applied Math & CS
http://shadowfaxrant.blogspot.com
Sent from my iPod

On Jun 17, 2010, at 7:31 PM, Bruce Cohen  wrote:


It's summertime, and I thought I would have time to build a Sage
server for my 65 (or so) calculus students.  I have a Ubuntu box
running 10.04 and using dynamic dns, I should be able to be able to
point my students to the site.  Using virtual box, I assume not much
damage can be done to the host machine.  Dan and Jason's
contributions

http://wiki.sagemath.org/DanDrake/JustEnoughSageServer
http://wiki.sagemath.org/SageVirtualBox

are a good place to start, but it have spent an entire afternoon
unsuccessfully get a VBox up and runner.

It appears that VBox has changed, I found this
http://tuxnetworks.blogspot.com/2010/05/howto-virtualbox-31-headless-on-lucid.html
blog on Vbox is be useful.

I am looking for more guidance.  Perhaps someone could make a VBox
appliance Sageserver available in much the same way as is currently
used  for local windoze machines.


We've switched back to using VMWare again. Probably the easiest would  
be to get a generic virtualbox image, and install Sage into it  
directly (either the binary or from source).


- Robert

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Re: [sage-edu] Discrete Math proof

2010-11-19 Thread Robert Bradshaw
On Thu, Nov 18, 2010 at 5:32 PM, A. Jorge Garcia  wrote:
> My Discrete Math students today came up with an observation: The
> average of any 3 consecutive terms of an arithmetic sequence equals
> the middle term.  So, I thought we'd show off some CAS in SAGE (this
> class uses python primarily) and wrote the following in my SAGE
> notebook:
>
> var('c,d')
> term1 = c+(n-1)*d
> term2 = c+(n+1)*d
> sum = term1+term2
> avg = expand(sum/2)
> show(term1)
> show(term2)
> show(sum)
> show(avg)
>
> and got the following output
> c+(n-1)*d
> c+(n+1)*d
> 2*c+2*n*d
> c+n*d
>
> So, I thought we'd try something similar with geometric sequences:
> var('c,d')
> term1 =a*r**(n-1)
> term2 = a*r*(n+1)
> prod = term1*term2
> avg = simplify(sqrt(prod))
> show(term1)
> show(term2)
> show(sum)
> show(avg)
>
> however, I got the following output
> a*r**(n-1)
> a*r*(n+1)
> a**2*r**(2*n)
> sqrt(a**2*r**(2*n))
>
> I couldn't get the final result to reduce to a*r**n, is there a way to
> do this?

Perhaps add some assumptions as to the positivity of your variables, e.g.


sage: var('a,r,n')
(a, r, n)
sage: assume(a>0)
sage: assume(r>0)
sage: assume(n>0)
sage: sqrt(a**2*r**(2*n))
sqrt(a^2*r^(2*n))
sage: simplify(sqrt(a**2*r**(2*n)))
r^n*a

- Robert

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Re: [sage-edu] Plotting trigonometric functions

2010-11-30 Thread Robert Bradshaw
I don't know the answer to your question, but I bet you'd have better
luck on sage-support.

On Tue, Nov 30, 2010 at 11:08 AM, Maura Murray  wrote:
> Hi,
>
> Is there an easy way to change the axes in plot so that the ticks are
> marked at intervals of pi/4 or pi/2?
>
> Thanks,
> Maura
>
> P.S.- If I've posted this question to the wrong forum, please let me
> know a better place to post the question. Thanks!
>
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Re: [sage-edu] Re: computerised exams?

2011-01-20 Thread Robert Bradshaw
On Wed, Jan 19, 2011 at 7:35 PM, David Joyner  wrote:
> On Wed, Jan 19, 2011 at 7:32 PM, dimpase  wrote:
>>
>>
>> On Jan 19, 7:37 pm, David Joyner  wrote:
>>> Will all these students take the exam in class simultaneously
>>> in a large computer lab?
>>>
>>
>> yes, that's the idea (well, we have 3 labs with total capacity over
>> 200 seats)
>
>
> Can you set up a Sage server locally,
> (a) create one worksheet worksheet_x per student x (that you own),
> the worksheet consisting of exam questions,
> (b) share worksheet_x with x
> (c) tell the student to save the work when they are done?

Even easier is to create one public worksheet that everyone must
manually copy into their account before editing. It's still pretty
easy to poke around and look at other people's worksheets if you know
how (via the filesystem, unless extra accounts are set up, and you
probably don't want to create 200 login accounts on the server) so I'd
say this works best with low-stakes problems where the goal is
experimentation. For code, I think projects usually make more sense
than exams.

- Robert

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Re: [sage-edu] cube roots in Sage

2014-06-19 Thread Robert Bradshaw
On Thu, Jun 19, 2014 at 9:39 AM, David Smith  wrote:
> I could live with nthroot -- but is cuberoot (or curt or cbrt) so different
> from sqrt?

Cubic roots are much less common. They don't even have their own
(unparameterized) symbol. I think some kind of a (real?) nth root
function makes sense.

> Anyway, it would be nice to have functions that resemble ones
> students see routinely without generating error messages.  I'm very much
> aware of the difficulties involved in reaching that goal, and I'll be
> patient.
>
> Still waiting for a solution on arcsec, as well.  There the issue is
> primarily plotting, although "integral" fails, even with a proper domain.
> numerical_integral works as it should.
>
> In the great scheme of things, these are certainly peripheral issues -- and
> they wouldn't be issues at all if textbook authors didn't feel obliged to
> drag in every function they know about.  As author, I'll guilty of that too
> (fear of the adoption committee), but in my defense, we only do these things
> in exercises.

It might not hurt to include a script for your students to copy/import
that makes common definitions you want.

> On Wednesday, June 18, 2014 8:48:36 PM UTC-4, kcrisman wrote:
>>
>> Just to chime in, as someone who has dealt with this question a lot
>> (though, perhaps ironically, never in a classroom situation):
>>
>> I would be very against a "cuberoot" function, but an "nthroot" function
>> where it was really clear what input was allowed could fly.  I appreciate
>> Greg's rationale.  Note however - what is the 0.1 power? Is that the same as
>> the 1/10 power?  This is a tricky floating point question to interpret.
>>
>> I don't think that the slowdown would be too bad since it would primarily
>> be for pedagogical purposes for plotting.
>>
>> David, I don't know how this would work with integrals, though - we'd have
>> to see if Maxima had something equivalent.  Perhaps it could do a temporary
>> set of the Maxima domain to real somehow, if that is what allows Maxima to
>> do the "right thing" in this context, I don't know.
>>
>> Thanks for fighting the good fight on trying to resolve this once and for
>> all!
>> - kcrisman
>
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