On Jul 24, 2:29 pm, Burcin Erocal wrote:
> [...]
> At Sage Days 24, I learned that Python allows the user to do arithmetic
> with bools:
>
> In [1]: 5+True
> Out[1]: 6
> [...]
> Any comments?
Preface: Python is my favorite language. These are just comments, no
flames please.
However, for the u
On Jul 25, 1:50 am, Marco Streng wrote:
> [...]
> I like the TypeError here to avoid bugs, but don't mind following
> python convention either.
http://docs.python.org/library/warnings.html
Maybe using (soft) warnings in the interim (while maintaining
workarounds) could be a compromise between g
> One possibility is we could split the file, then you download each part
> separately. Then the md5 checksum of each part could be checked individually.
> If
> one gets corrupted, only that part would need to be downloaded again. You
> would
> of course need to rebuild the constituent parts.
It
> > It may be easier to enable a bittorrent server on a mirror. [...]
>
> Possibly, but that's more hassle in the short term. I don't know what's
> involved. In any case, I can't do it as I don't control the server.
Well, there are no perfect solutions, but it is an option. Maybe in 5
or 10 years
> i.e. the following produces no output:
> sage: 42;
>
> However, in doctests, it *does* produce output, the same line in a
> doctest would give:
> **
> File "/home/jdemeyer/printtest.sage", line 6:
> sage: 42;
> Expected nothi
> [1]http://www.sagemath.org/mirror/win/meta/sage-vmware-4.4.alpha0.zip.me...
> [2]http://aria2.sourceforge.net/
>
> I'm not aware of a better solution to handle this problem ...
>
> H
Harald:
I think metalinks are great, indeed, the metalink file you reference
contains a torrent file reference
SageDevs,
In the interest of "gotchas", please consider the following:
The built-in str, and the module string are different, though both
return type str according to type().
Example:
d...@dv9000-laptop:~$ python2.6
Python 2.6.4 (r264:75706, Dec 7 2009, 18:43:55)
[GCC 4.4.1] on linux2
Type "he
Caveat: Hopefully my chaining of operators there didn't mislead, that
was unintended. I think most of what I said still holds, if not all.
-Don
On Aug 2, 9:14 am, mda_ wrote:
> SageDevs,
>
> In the interest of "gotchas", please consider the following:
>
> Th
Another Caveat: str doesn't implement .__copy__ or .__deepcopy__ so
I'm being sillybut the main point being "is" is object comparison
not equality. Ok, email on exponential backoff!! ;-)
On Aug 2, 11:06 am, mda_ wrote:
> Caveat: Hopefully my chaining of operators the
bad form unless you are working with an object that is
mutable. I hope it's not making a double reference, that would be bad
design.
I apologize for glossing over your explicit statement that str are
immutable. Indeed. I could have reduced my emails by [4,3].
On Aug 2, 1:22 pm, mda_ wrote
> str is very much immutable.
> So you can't even set some custom attribute.
I found a way to cheat. =)
Python 2.6 has backported the Python 3000 bytearray() method, which is
basically just a mutable str. No import statement needed.
http://www.python.org/dev/peps/pep-3112/
So you can copy yo
I wrote the following zumkeller number verification function today, if
anyone's interested. I verified its correctness for the first 10,000
terms (from the OEIS site) in the domain: 1 < n < 43465. Computation
for that range took 1 hour, 26 minutes, 5.17 seconds =) Is it fast or
slow?
def is_zk(
> Calling sigma() involves a call to factor(), so you are basically
> factoring your input *twice* every time (I think; someone should correct
> me if I'm wrong) -- bad idea! I would move the "d
> = divisors(a)" to the top, and then do
>
> sa = sum(d)
You're right, I made that same optimizatio
Also I forgot to parallelize it. It currently only runs on one core.
I have two on this laptop. =)
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On Aug 3, 7:38 am, YannLC wrote:
> Here is my version,
Thanks Yann!
I'm going to write a version in Cython. A guy on the OEIS list got
about a 100x speed up with shedskin. Pypy was close to the shedskin
mark, and he never finished his Cython port (properly) to judge Cython
fairly.
> def is_z
> I still like returning the number instead of True.
I take it back. I'm wrong, as noted in the other thread. I can't
assume the caller will coerce the return type with bool().
Can I get an A for effort? =)
Had a bad day..
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> No need to call is_prime(a), divisors would only return length two;
> otherwise the sieving is done twice. (Unless Sage does something
> extra smart behind the scenes.)
What I said above is wrong, remembering there are faster algorithms,
and digging through rings/integer.pyx I see hybrid is_pri
Wow, thanks. I didn't see your post just as I sent my retraction.
I'll definitely play with this some tonight. I'm going to calculate
very far, then do an intersection with is_squarefree() just out of
curiousity.
On Aug 3, 5:26 pm, YannLC wrote:
> Here is a cython version suitable only for ints
Wow, I'm 100% certain I have nothing to add to this quandary, and
couldn't possibly know the correct answer/choice, only supply the link
to the relevant context Robert refers to:
http://docs.python.org/release/3.0.1/whatsnew/3.0.html#ordering-comparisons
Down the rabbit hole indeed.
D
On Aug 4,
> An alternative approach would be to realise that vertices need to be
> stored in a sequence that has quick membership testing, for instance a
> dictionary {'v1': 0, 'v2':1} etc. Depending on the type of access,
> perhaps you would also need to keep the thing as a sequence
> ['v1','v2']. In magma,
> > I don't know how easy it is to make such a data structure efficient
> > and what the memory penalty is for having both hashing and ordering.
>
> http://docs.python.org/py3k/whatsnew/3.1.html#pep-372-ordered-diction...
>
> The reference implementation in the PEP(372) states "O(n)" for
> deletion
> Another except from the PEP: "A version written in C could use a
> linked list. The code would be more complex than the other two
> approaches but it would conserve space and would keep the same big-oh
> performance as regular dictionaries. It is the fastest and most space
> efficient."
The trad
> Hopefully this all agrees with you, and if not, I guess I can start
> learning Lisp...
My apologies for the cross-posting (I am not yet approved for sage-
flame)
http://www.buayacorp.com/wp-content/uploads/2007/10/john-mccarthy-poster1.jpg
(Above: A portrait, and tribute! ;-), to the inven
> The fact that you're "doing it" at all implies the imperative which, as
> we all know, is not the way to program (this week).
http://en.wikipedia.org/wiki/Touché
my friend(?)
=)
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> > - LD_LIBRARY_PATH means people must either mess big-time with
> > environment variables, or start using "sage -python" and "sage -
> > ipython" (in which case all the examples about using Python from the
> > internet, scripts with shebangs "#!/usr/bin/env python" etc. stops
> > working).
>
> W
> >>ordering, I'm just suggesting that since there is an inconsistent
> >> definition of < for Sage sets, and since they get used frequently as
> >> vertices, that we define atotalordering. You yourself admitted that
> >> you can't think of a natural mathematical meaning for < for arbitrary
> >> s
> There's going to get some examples to look at, and they are going to be decent
> ones. They make Mathematica look very easy - only later do you find out that
> its
> far from a trivial program to use well.
Programming isn't trivial in general. Python is very productive
precisely because of its
On Aug 16, 12:39 am, Tom Boothby wrote:
> > I just wrote a worksheet that I'd be willing to share in this manner
> > (and release to public domain, cc, etc). I'll have to add some
> > documentation, but other than that, it's ready to go.
>
> Money where my mouth is:
>
> http://sagenb.org/home/pub
> On Aug 16, 12:39 am, Tom Boothby wrote:
>
> > > I just wrote a worksheet that I'd be willing to share in this manner
> > > (and release to public domain, cc, etc). I'll have to add some
> > > documentation, but other than that, it's ready to go.
>
> > Money where my mouth is:
>
> >http://sagen
> system to be more modular. Is there even an efficient method in Python
> of conditionally including code based on availability of prereqs? I
Since I'm a sage-noob, I don't know if my answer is relevant
enoughHowever, the import statement in python, in general, has
been misused in the past.
On Jul 31, 6:22 pm, Mike Hansen wrote:
>[...]
> Again, please stop spreading FUD about the category code.
>
> --Mike
Isn't the FUD acronym trademarked and copyrighted by the GNU
folks? ;) Tom Boothby: What new word(s) can you create to describe
these "Inter-License Affairs"? If the SAGE acrony
sage: is_triangular_number(0)
0
sage: is_triangular_number(1)
1
sage: is_triangular_number(2)
False
sage: is_triangular_number(3)
2
This is the same duck-typing style choice I made before. Example
where unexpected output is generated:
sage: [x for x in [0..3] if not is_triangular_number(x)]
[0,
sage: is_even(e)
TypeError: unsupported operand type(s) for %:
'sage.symbolic.constants_c.E' and 'int'
sage: is_even(float(e))
False
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F
On Sep 8, 5:12 pm, mda_ wrote:
> sage: is_even(e)
> TypeError: unsupported operand type(s) for %:
> 'sage.symbolic.constants_c.E' and 'int'
>
> sage: is_even(float(e))
> False
sage: is_odd(float(e))
True
sage: is_odd(int(e))
False
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Also,
sage: float(e^(-pi/2))
0.20787957635076193
The last digit should be 1, since
i^i = 0.20787957635076190854
sage does not recognize this identity:
sage: e^(-pi/2) == i^i
e^(-1/2*pi) == I^I
("True" expected as output.)
What's the best way to ask sage for floating point approximatio
On Sep 12, 5:44 pm, Mitesh Patel wrote:
>[...]
> This appears to work:
>
> sage: bool(e^(-pi/2) == i^i)
> True
Thanks Mitesh. What is the sage convention for returning the object
as a result of "==" instead of bool when the result is not False? Is
it ad hoc?
Would you consider float(i^i) rais
On Sep 13, 5:53 pm, Mitesh Patel wrote:
> On 09/12/2010 10:19 PM, mda_ wrote:
>
> > On Sep 12, 5:44 pm, Mitesh Patel wrote:
> >> [...]
> >> This appears to work:
>
> >> sage: bool(e^(-pi/2) == i^i)
> >> True
>
> > Thanks Mitesh. W
On Sep 21, 10:39 am, "Dr. David Kirkby"
wrote:
> On 09/21/10 06:12 PM, Niles wrote:
>
> > I'd just like to comment that, if the wording "nearest Mathematica
> > equivalent" is going to be an essential part of this, then it should
> > be very carefully chosen, and probably implemented through some
> > How about "close analogue".
>
> No, I don't like that. If nothing else, it will be more confusing to those
> whose
> first language is not English, and even though mine is, I don't like that
> term.
Tom Boothby can "inventor" a word. I do like "analogues" though.
m-w.com: "1:something tha
On Sep 25, 4:17 am, YannLC wrote:
> sage: sloane.A111776 seems to be in fact (almost)
> A109814.http://www.research.att.com/~njas/sequences/A109814
New Ticket #10025
http://trac.sagemath.org/sage_trac/ticket/10025
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