[sage-devel] Re: BUG??? in function "implicit_plot"

[Dox]

I found the answer... to use the option "aspect_ratio='automatic'".

Thank you!

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[sage-devel] Re: BUG??? in function "implicit_plot"

[Dox]

I found the answer... to use the option "aspect_ratio='automatic'"

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[sage-devel] BUG??? in function "implicit_plot"

[Dox]

Dear all, I'm trying to plot an implicit function with a "y"-axis range 
three orders of magnitude greater than the range of the "x"-axis. 

If I use logarithmic scale, the resulting plot is the one shown in 
"sage0.png"... However, when a linear scale is used, the plot collapses 
(see the file "sage1.png")

I would say this is a BUG, because the expected result should be an 
automatic linear scaling of the "y"-axis. But I could be misusing the code.

THX


CODE:

sage: reset()
sage: var('MN', domain='positive', latex_name=r"M_N")
sage: var('Vtausq', domain='positive', latex_name=r"\left|V_{\tau N}\right|^2")
sage: var('MWR', domain='positive', latex_name=r"M_{W_R}")


sage: mmu = 0.105  # GeV
sage: mtau= 1.7# GeV
sage: Eff = 1  # To be scaled
sage: Nevents = 5  # Number of observed events
sage: Ntaus   = 4.9E8  # Taus generated on the experiment (ShiP??)
sage: npot= 2E20   # Potential number of events
sage: xcc = 4.5E-4 #
sage: BrDs  = 0.0554  # Branching ratio D_s -> tau + nu_tau
sage: Brtau = 1   # Branching ratio tau -> X + nu_tau
sage: BrN   = 0.036   # Branching ratio N -> mu + mu + nu
sage: BB   = BrDs * Brtau * BrN * (80.385/MWR)^4 * ( 1 - (MN/mtau)^2 ) * ( 1 - 
(2*mmu/MN)^2 ) * heaviside(MN - 2*mmu) * heaviside(mtau - MN) 
sage: edet = 8E-5 * MN^5 * 1E7 * (80.385/MWR)^4 * Eff
sage: eq = npot * 2 * xcc * BB * edet - Nevents
sage: eq

sage: G = Graphics()
sage: G = implicit_plot(eq, (MN,.1,2), (MWR,5E3,11E3), scale=('semilogy',2)) 
sage: G

sage: G1 = Graphics()
sage: G1 = implicit_plot(eq, (MN,.1,2), (MWR,5E3,11E3)) 
sage: G1

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[sage-devel] How could I use a general connection with SageManifold?

[Dox]

Hi dear community:

I've seen the examples given in the homepage of 
sagemanifolds, 
and still have not a clue about how to use (or define) a general 
connection, because all the examples work with the Levi-Civita connection.

Does anyone knows how to work with a general connection?

Thank you.

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[sage-devel] Re: SageManifolds: differential geometry and tensor calculus in Sage

[Dox]

Thx Michael, I didn't know that feature of sage notebook!

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[sage-devel] Re: SageManifolds: differential geometry and tensor calculus in Sage

[Dox]

I'm trying to reproduce the examples in the page, starting with 
"Schwarzschild spacetime"

So far I'm getting the following:

* When defining a `Chart`, say `X`, t
from manifolds.all import *
M = Manifold(4, 'M', r'M'); M
X = Chart(M, r't, r:positive, th:positive:\theta, ph:\phi', 'BL')
X
does not return the latex output, but this

chart 'BL' (t, r, th, ph)

this is not a problem because after trying 
X.show()
the expected output pops up!

When using the `show()`method on the metric the output is not shown in the 
way I expected (with the tensor product of the basis,
g[0,0], g[1,1], g[2,2], g[3,3] = -(1 - 2*m/r), 1/(1 - 2*m/r), r^2, (r*sin(th
))^2; show(g)

g = (2*m/r - 1) dt*dt - 1/(2*m/r - 1) dr*dr + r^2 dth*dth +
r^2*sin(th)^2 dph*dph

I try a couple of things and non of them yields the result shown in the 
documentation. Similar behaviour goes on and on through the WS.

* I'd add the following line to the WS
nab[:]
because people can see the components of the connection.

* Additionally, I shall propose to define a method to show only the 
non-trivial components of the tensors... including the `name` of the 
component (in indices). The code below will do the work, but of course it 
can be improved.
for i in M.irange():
for j in M.irange():
for k in xrange(j,M.dimension()):
if (nab[:][i][j][k] != 0):
print "Gam_{%d %d %d}: "  %(i, j, k)
print "\t", nab[:][i][j][k], "\n\n"
This method should be implemented for tensors.

I'm still learning the stuff, and should be posting more suggestions later! 
Thank you for the wonderful work done with this package!!! Cheers



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[sage-devel] Re: SageManifolds: differential geometry and tensor calculus in Sage

[Dox]

I just installed SageManifolds package, and tried 

> sage: Chart?

to review the documentation, and the format is not OK, Is it just me or a 
documentation `bug`?


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[sage-devel] Re: SageManifolds: differential geometry and tensor calculus in Sage

[Dox]

Impressive work! I started improving my programming skills to try 
implementing the Hodge star on DifferentialForms, I see you went much 
further!

I'll immediately install the package, working on several examples, and asap 
start contributing with it!

Congratulations! 

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Re: [sage-devel] Re: _cleanup method in DifferentialForms class

[Dox]

I could try to change something... However, What is the way to provide a 
patch? Is it through github?

On Friday, 28 June 2013 09:36:47 UTC-4, Joris Vankerschaver wrote:
>
>
> Symbolic expressions have a .is_trivial_zero() method which is more 
>> suitable for use here. It doesn't try anything advanced so it has 
>> predictable runtime. 
>>
>
> I just wanted to say that I had no idea that this function existed when I 
> wrote that code, and it seems like a good idea to use it here. If anybody 
> wants to fix this, great, otherwise I'll do it myself in a few days when I 
> have time.
>
> All the best,
> Joris 
>  
>

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[sage-devel] _cleanup method in DifferentialForms class

[Dox]

Dear developers,

I was looking through the class DifferentialForm, and there is a note in 
the `__eq__` method pointing that "...most of the execution time is spent" 
in cleaningpu the differential forms
def __eq__(self, other):
if type(other) == type(self):
if self._degree != other._degree:
return False
else:
# TODO: the following two lines are where most of the 
# execution time is spent.  
self._cleanup()
other._cleanup()

if len(self._components) != len(other._components):
return False

# We compare the component dictionary of both differential 
# forms, keeping in mind that the set of keys is 
# lexicographically ordered, so that we can simply iterate 
# over both dictionaries in one go and compare (key, value) 
# pairs as we go along.

for (key1, val1), (key2, val2) in \
zip(self._components.iteritems(), \
other._components.iteritems()):
if key1 != key2 or str(val1) != str(val2):
return False
return True
else:
return False



Then, I found the `_cleanup` method

def _cleanup(self):
r"""
Helper function to clean up self, i.e. to remove any
zero components from the dictionary of components.

EXAMPLES::

sage: F = DifferentialForms()
sage: f = DifferentialForm(F, 1)
sage: f[0] = 0
sage: f[1] = 1
sage: f[2] = 0
sage: f._dump_all()
{(2,): 0, (0,): 0, (1,): 1}
sage: f._cleanup()
sage: f._dump_all()
{(1,): 1}

"""
zeros = []

for comp in self._components:
if self._components[comp].is_zero():
zeros.append(comp)

for comp in zeros:  
del self._components[comp]  

And I wonder... Is it possible to delete directly the `zeros` from `self`? 
I guess it was not done like that because it is not possible!

However, then it occur to me that copying `self` to `other` and then 
reassign to `self` only the notzero component could be faster

Is it possible?

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[sage-devel] Re: Paper publication of the book "Calcul Mathematique avec Sage"

[Dox]

Great work! Congratulations!

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Re: [sage-devel] Defining Clifford Algebras

[Dox]

Hi David,

Thank you for pointing out such an interesting feature of SymPy. I've been 
checking the documentation, and it seems to do nice things, but I feel it a 
bit extrange... the notation and the usage in not quite clear.

Although I tried some of the examples in the documentation and got no 
output. (of course I could be doing something wrong).

However, it seems a good start point for implementing what I'd like to have.

Thank you again. Cheers.

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[sage-devel] Defining Clifford Algebras

[Dox]

Dear all,

I've asked in asksage how to define a Clifford 
Algebra. 
Benjaminfjones has suggested I start by looking at the Quaternion algebras 
code, 
while Burcin has directed my attention toward the GiNac package.

Due to my lack of knowledge about GiNaC, I somehow prefer the first option. 
And moreover, I am thinking that would be nice to write a little code say 
SAGE native... to managing Clifford algebras.

I have never done something like this, thus I'm asking for help.

*Questions

*
   
   1. How should I define objects which inherit the properties of an 
   associative algebra?
   2. In the quaternionic case, there are 2 basic objects (thought as 
   generators of a Clifford algebra), which generate the basis of the algebra 
   (4 elements, to know 1, i, j, k.). For more general Clifford algebras I 
   would like to name the basic elements $e_1, e_2, ...$ whist the basis could 
   be $e_{12}, e_{13}, ...$ and so on. How could this be done? *Note* that 
   in dimension *D* there are $2^{|D/2|}$ elements in the basis.

I know this is a long term work, thus I shall be asking more in the future. 
I thank any help I can get.


Cheers.

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[sage-devel] Re: Defining anti-commutator

[Dox]

Thank you Simon, a very complete answer to my problem.

I've already tested my definition and is fantastic.

Cheers!

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Re: [sage-devel] Defining anti-commutator

[Dox]

Thank you for the tip! That's an impressive command.

Cheers.

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[sage-devel] Defining anti-commutator

[Dox]

Dear all,

I'm interested in defining the anti-commutator (function or method) for 
matrices. I look up the definition of the commutator, and it's very simple

def acomm(self,other):
return self*other + other*self 

providing (of course) the additional information about the usage.

However I tried to add this function to my sage-test branch... and I 
couldn't find where the methods for matrices are. 

Where should I include this changes?

Thx.

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[sage-devel] Re: Problems with "full output"

[Dox]

Yes Nils, In fact it was a browser problem. William makes me notice it.

Thank you all.

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[sage-devel] Re: Problems with "full output"

[Dox]

Sorry It's not getting updated.

On Monday, 8 October 2012 12:14:42 UTC-3, Simon King wrote:
>
> Hi! 
>
> On 2012-10-08, Dox > wrote: 
> > --=_Part_110_6376496.1349698687928 
> > Content-Type: text/plain; charset=ISO-8859-1 
> > ... 
> > I noticed that after changing the variables, and rerun the calculation 
> the 
> > full_output.txt is now getting updated. 
> > 
> > I guess this is a bug. 
>
> Why? 
>
> If one reruns a calculation, then I'd certainly expect that the output 
> (both what is printed on screen and full_output.txt) is getting updated. 
>
> Or is there a misspelling in your post? Should "...is now getting updated" 
> be "...is not getting updated"? 
>
> Best regards, 
> Simon 
>
>
>

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[sage-devel] Problems with "full output"

[Dox]

Dear community:

I was doing some simple linear algebra calculations, and since the output 
was a long list, Sage gave me a few lines with the option of looking at the 
full_output.txt file.

I noticed that after changing the variables, and rerun the calculation the 
full_output.txt is now getting updated.

I guess this is a bug. Has anyone experienced the same? Should I open a 
trac?

OS: Ubuntu 12.04.1
arch: 64-bits
SAGE: 5.3
browser: Firefox 15.0.1

Cheers

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Re: [sage-devel] Installing Sage 5.0.1 on Ubuntu 12.04

[Dox]

Thank you Jan, It worked.

I'll compile the source, but I have a doubt, How many cores are in a i7? 4 
or 8?

Dox

On Wednesday, 27 June 2012 16:49:41 UTC-4, Jan Groenewald wrote:
>
> Hi Dox,
>
> On 27 June 2012 22:16, Dox  wrote:
>
>> Dear all:
>> I bought a new laptop yesterday, and it has arch. 64-bits. So, I download 
>> Sage 5.0.1 for Ubuntu 10.04 although it's running Ubuntu 12.04.
>> After the extraction of the pack, I tried as usual (Since v.3), but I'm 
>> getting the error "ERROR:root:code for hash md5 was not found." that so 
>> many people is complaining about.
>> I've also found a post in AskSage, so I installed
>>
>>- m4 
>>- g++ 
>>- gfortran 
>>- libssl-dev 
>>- dh-exec 
>>- dpkg-dev
>>
>> deside the usual perl, make, and so on.
>>
>> Nonetheless, the error holds.
>>
>> What can I do? Should I try to install from the PPA repository?
>>
>> Thank you!
>>
>> P.D.: Additionally I would like to compile the source for a i7 intel, How 
>> many cores should I tell ATLAS to use, 4 or 8?
>>
> Just a guess:
>
> sudo apt-get install libssl0.9.8 (the default on 12.04 is 1.0.0; sage 
> needs 0.9.8).
>
> I'll be updating the PPA soon.
>
> However, with your i7 CPU, why not compile from source?
>
> Regards,
> Jan
>
>
> -- 
>   .~. 
>   /V\ Jan Groenewald
>  /( )\www.aims.ac.za
>  ^^-^^ 
>
>

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[sage-devel] Installing Sage 5.0.1 on Ubuntu 12.04

[Dox]

Dear all:

I bought a new laptop yesterday, and it has arch. 64-bits. So, I download 
Sage 5.0.1 for Ubuntu 10.04 although it's running Ubuntu 12.04.

After the extraction of the pack, I tried as usual (Since v.3), but I'm 
getting the error "ERROR:root:code for hash md5 was not found." that so 
many people is complaining about.

I've also found a post in AskSage, so I installed

   - m4 
   - g++ 
   - gfortran 
   - libssl-dev 
   - dh-exec 
   - dpkg-dev
   
deside the usual perl, make, and so on.

Nonetheless, the error holds.

What can I do? Should I try to install from the PPA repository?

Thank you!

P.D.: Additionally I would like to compile the source for a i7 intel, How 
many cores should I tell ATLAS to use, 4 or 8?


DOX

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[sage-devel] Irreps of Lie groups

[Dox]

Dear all,
a couple of weeks ago I wrote a small program for computing the irreps
of a Lie group,
http://sagenb.org/home/pub/4395/
I'd like to help implementing it for future versions of SAGE...
However, I guess it needs a lot of work for the sake of optimization.

* Could you help me optimize it?

* Where should it be included as a class? (in case it is possible)

Thank you!

DOX

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[sage-devel] Re: vector products

[Dox]

You're very right! Sorry

On Jan 24, 1:06 pm, Jason Grout  wrote:
> On 1/24/12 9:56 AM, Dox wrote:
>
> > Hi Jason,
>
> > Thank you for the suggestion. Nonetheless, the first does not work...
> > I venture to guess that SAGE understand the product (*) as commutative
> > for vectors... or somehow it is rearranged.
>
> u1.column()*u2.row() gives a 3x3 matrix.  u1.row()*u1.column() gives a
> 1x1 matrix, of course.  These work in Sage 4.7.2.
>
> Jason

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[sage-devel] Re: vector products

[Dox]

Hi Jason,

Thank you for the suggestion. Nonetheless, the first does not work...
I venture to guess that SAGE understand the product (*) as commutative
for vectors... or somehow it is rearranged.

The outer_product is OK!

Thank you so much!

On Jan 24, 12:06 pm, Jason Grout  wrote:
> On 1/24/12 8:57 AM, Dox wrote:
>
>
>
>
>
>
>
>
>
> > Hi everyone,
>
> > Today I rediscover a "problem" with the product of vectors.
>
> > I've defined two vectors u1 and u2,
>
> > sage: u1 = vector([a,b,c])
> > sage: u2 = vector([d,f,g])
>
> > then I try to construct the matrix u1*u2.column()
>
> > sage: M = u1*u2.column()
> > sage: show(M)
>
> > but it interprets the command as a vector product and gives and
> > scalar, instead of a matrix.
>
> > How can this be solved?
>
> u1.row()*u2.column()
>
> or u1.outer_product(u2)
>
> (I haven't tested either of those...)
>
> Thanks,
>
> Jason

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[sage-devel] Re: vector products

[Dox]

Thx, this is it!

On Jan 24, 12:01 pm, David Joyner  wrote:
> On Tue, Jan 24, 2012 at 9:57 AM, Dox  wrote:
> > Hi everyone,
>
> > Today I rediscover a "problem" with the product of vectors.
>
> > I've defined two vectors u1 and u2,
>
> > sage: u1 = vector([a,b,c])
> > sage: u2 = vector([d,f,g])
>
> > then I try to construct the matrix u1*u2.column()
>
> > sage: M = u1*u2.column()
> > sage: show(M)
>
> > but it interprets the command as a vector product and gives and
> > scalar, instead of a matrix.
>
> > How can this be solved?
>
> Do you mean the tensor product?
>
> sage: u1 = vector([1,2,3])
> sage: u2 = vector([-1,1,2])
> sage: u1.tensor_product(u2)
> [-1  1  2]
> [-2  2  4]
> [-3  3  6]
>
>
>
>
>
>
>
>
>
> > Thank you guys!
>
> > DOX.
>
> > --
> > To post to this group, send an email to sage-devel@googlegroups.com
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> > sage-devel+unsubscr...@googlegroups.com
> > For more options, visit this group 
> > athttp://groups.google.com/group/sage-devel
> > URL:http://www.sagemath.org

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[sage-devel] vector products

[Dox]

Hi everyone,

Today I rediscover a "problem" with the product of vectors.

I've defined two vectors u1 and u2,

sage: u1 = vector([a,b,c])
sage: u2 = vector([d,f,g])

then I try to construct the matrix u1*u2.column()

sage: M = u1*u2.column()
sage: show(M)

but it interprets the command as a vector product and gives and
scalar, instead of a matrix.

How can this be solved?

Thank you guys!

DOX.

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[sage-devel] Re: Plotting a dirac_delta

[Dox]

Hi kcrisman,

A very useful command that spike_function, but I still don't get how to use 
it as a delta_function, Could you help me with an example? say,

delta_function(log(2+sin(x)))

Thank you,
   Dox

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Re: [sage-devel] Plotting a dirac_delta

[Dox]

Hi Benjamin,

Yes, I'd like to get an automatic plot like that, where the singularity can 
be seen. For example, if I try

sage: var('x')
sage plot(1/x, (x,-2,2), detect_poles=False)

the singularity is shown. But it does not work with the delta distribution. 
Any suggestions? 

Dox

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[sage-devel] Plotting a dirac_delta

[Dox]

Hi group!

I'm trying to plot a dirac_delta function, with the command

sage: var('x')
sage: plot(dirac_delta(x), (x,-1,1), detect_poles=False)

and I get just a line through the x axis. Can this function be plotted with 
the singularity? because I'd like to plot a more complex function and detect 
the singular behaviour by looking at it!

Thx.!!!

Dox

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[sage-devel] Re: Integration of dirac_delta

[Dox]

Thx kcrisman!

very useful workaround.

Dox

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[sage-devel] solve an algebraic expression

[Dox]

Hi again list,

This time I come with a problem of solving an algebraic expression, the 
solution has the variable x on it!

sage: reset()
sage: var('x')
sage: var('mp', latex_name=r"m_\pi")
sage: var('me', latex_name=r"m_e")
sage: f(x) = mp - sqrt(x^2 + me^2) - x
sage: solve(f(x)==0, x)
[x == mp - sqrt(me^2 + x^2)]

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[sage-devel] Integration of dirac_delta

[Dox]

Hi group!

I was trying to integrate a dirac_delta, but SAGE cannot do so... weird 
thing, 'cause that `function' is defined, and in only make sense as part of 
an integration.

Cheers.

Dox.

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[sage-devel] Re: translate to python

[Dox]

Hi Simon, thank you for your quick answer, It's almost what I expected, but 
in fact the arctan function is denoted by atan in python. Of course it's 
possible to correct it by hand, but it's easy to mistype when the 
expressions are too complicated.

Dox.

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[sage-devel] translate to python

[Dox]

Hi group,

I know that for a given expression it's possible to translate it to LaTeX. 
Is it possible to translate it to python?

Say, from x^2*arctan(x) get x**2*atan(x)

Thx.

Dox.

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[sage-devel] Re: MathJax

[Dox]

Looks nice... Thx for the recommendation.

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[sage-devel] Differentials are defines

[Dox]

Hi group!

I'm trying to change the metric from Euclidean to Spherical. I know there 
are several ways of doing so, but I'd like to do something like this:

   1. Define the new coordinates var('phi')
   2. Give the relation between old and new coordinates x = cos(phi) and y = 
   sin(phi)
   3. Finding the differentials, dx and dy
   4. Compute dx^2 + dy^2

Is it possible to define differentials of functions? If so, How?

Thx.

DOX

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[sage-devel] Re: Series expansion.

[Dox]

Thank you very much guys! 

Dox.

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[sage-devel] Series expansion.

[Dox]

Hi everyone!

I'd like to know if there is a way of finding the series expansion of a 
given function around zero and infinity, Is it possible?

I tried with sympy.series, didn't work

sage: reset()
sage: from sympy import *
sage: r = Symbol('r')
sage: sympy.series(2*r/sinh(2*r), r)

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[sage-devel] Re: Bundle different objects

[Dox]

Any other contribution?

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[sage-devel] Re: Signature of a permutation

[Dox]

Wow!

A lot of answers!

Thank you everyone, :-) nice to see so much different contributions!

Dox

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Re: [sage-devel] Re: Signature of a permutation

[Dox]

Thank you Mike! :-)

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[sage-devel] Re: Signature of a permutation

[Dox]

Hi again people!

Just wanted to know if the Levi-Civita tensor can be emulated by using this,
 

sage: G = SymmetricGroup(4)
sage: G([4,2,3,1]).sign()
-1


because I'm not sure if the notation used in the documentation is equivalent 
to mine!

Thx.

Dox
 

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[sage-devel] Signature of a permutation

[Dox]

Hi guys!

Short question! Is there any function equivalent to the *Levi-Civita*
 symbol?

I found *Eijk* in sympy... but seems to work only in 3-dimensions.

Thank you!

Dox

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[sage-devel] Re: Bundle different objects

[Dox]

I've define the action of the exterior derivative on the non-Abelian
connection,

class nAform(object):
def __init__(self, a, b):
self._form = a
self._matrix = b

def __add__(self, other):
if isinstance(other, nAform):
if (self._matrix == other._matrix):
return nAform(self._form + other._form, self._matrix)
else:
raise NotImplemented
raise NotImplemented

def __mul__(self, other):
if isinstance(other, nAform):
return nAform(self._form.wedge(other._form),
self._matrix.commutator(other._matrix))
raise NotImplemented

def diff(self):
return nAform(self._form.diff(), self._matrix)

def __repr__(self):
return str((self._form, self._matrix))

def __str__(self):
return self.__repr__()

* TODO:
** Define the sum for forms with values in different elements of the
algebra.
** Define the product of the forms by a number (or function)

Cheers

 DOX

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[sage-devel] Re: Bundle different objects

[Dox]

Nicalas... Your suggestion almost work, and in fact it is exactly what
I'm talking about!

Specifically, my idea is to work with connections with values in a non-
Abelian Lie algebra, SU(2), so there are 3 generators.

Therefore, the first entry of my function is a form, and the second is
a Lie algebra generator!.

I tried this

class nAform(object):
def __init__(self, a, b):
self._form = a
self._matrix = b

def __add__(self, other):
if isinstance(other, nAform):
if (self._matrix == other._matrix):
return nAform(self._form + other._form, self._matrix)
else:
raise NotImplemented
raise NotImplemented

def __mul__(self, other):
if isinstance(other, nAform):
return nAform(self._form.wedge(other._form),
self._matrix.commutator(other._matrix))
raise NotImplemented

def __repr__(self):
return str((self._form, self._matrix))

def __str__(self):
return self.__repr__()

And for monomials form it can multiply. But I got stacked in the
definition of an addition, if the generators of the algebra are
different! Which is, of course, one of the most important part of the
class.

Any additional help is welcome!

DOX

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[sage-devel] Re: Bundle different objects

[Dox]

I already define my class, and starts Ok, I have changed the operation
to __mul__. But now I'd like to define an __add__ operation which
surpass my knowledge...

Something like this,
sage: A = MyClass( 3, "Hello")
sage: B = MyClass( 4, "World!")
sage: A+B
( 3, "Hello") + ( 4, "World!")

sage: C = MyClass( 5, "World!")
sage: B+C
( 9, "World!")

I'm thinking could be a bit hard, since the function I'm defining has
not a string but a matrix as second entry. The first is not a number
either.

Thx.

Dox.


On Feb 10, 3:42 am, Jason Grout  wrote:
> On 2/9/11 9:18 PM, Robert Bradshaw wrote:
>
> > On Wed, Feb 9, 2011 at 6:43 PM, Dox  wrote:
> >> Hi people!
>
> >> I was wondering if there is a way of bundle two kind of different
> >> objects together and define operations on them.
>
> >> Suppose, I'd like to bundle a number and a string (3, Hello) and (4,
> >> World!!)... then define and operation which multiplies the numbers and
> >> add strings, so the result is (12, HelloWorld!!)
>
> >> Something like that!
>
> > Yes. See, for example, how the sage.misc.preparser.BackslashOperator
> > is implemented. (I think we have a more generic one, but I'm not sure
> > where it is.)
>
> I presume you mean the infix decorator from this patch:
>
> http://trac.sagemath.org/sage_trac/ticket/6245
>
> I was going to point out the page in the reference manual, but
> apparently somehow that file is not documented in the reference manual.
>
> Anyways, do infix_operator?, see sage.misc.decorator, or just look at
> this example:
>
> sage: @infix_operator('add')
> : def my_add(a,b):
> :     return (a[0]*b[0], a[1]+b[1])
> :
> sage: (3,"Hello") +my_add+ (4, "World!!")
> (12, 'HelloWorld!!')
>
> But it might make a lot more sense to make a simple class that prints
> out the string and number and has an operation defined on it.
>
> sage: class MyClass:
> :     def __init__(self, num, s):
> :         self._num=num
> :         self._s=s
> :     def __add__(self, other):
> :         if isinstance(other, MyClass):
> :             return MyClass(self._num*other._num, self._s+other._s)
> :         raise NotImplemented
> :     def __repr__(self):
> :         return str((self._num, self._s))
> :     def __str__(self):
> :         return self.__repr__()
> :
> sage: a=MyClass(3,"Hello")
> sage: b=MyClass(4,"World!!")
> sage: a
> (3, 'Hello')
> sage: b
> (4, 'World!!')
> sage: a+b
> (12, 'HelloWorld!!')
>
> Thanks,
>
> Jason

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[sage-devel] Re: Bundle different objects

[Dox]

Wow!!!

Jason, you're a genius!!! :-)

Thank you for such a complete answer. Now I'll try to define my own
class... :-P

Dox.

On Feb 10, 3:42 am, Jason Grout  wrote:
> On 2/9/11 9:18 PM, Robert Bradshaw wrote:
>
> > On Wed, Feb 9, 2011 at 6:43 PM, Dox  wrote:
> >> Hi people!
>
> >> I was wondering if there is a way of bundle two kind of different
> >> objects together and define operations on them.
>
> >> Suppose, I'd like to bundle a number and a string (3, Hello) and (4,
> >> World!!)... then define and operation which multiplies the numbers and
> >> add strings, so the result is (12, HelloWorld!!)
>
> >> Something like that!
>
> > Yes. See, for example, how the sage.misc.preparser.BackslashOperator
> > is implemented. (I think we have a more generic one, but I'm not sure
> > where it is.)
>
> I presume you mean the infix decorator from this patch:
>
> http://trac.sagemath.org/sage_trac/ticket/6245
>
> I was going to point out the page in the reference manual, but
> apparently somehow that file is not documented in the reference manual.
>
> Anyways, do infix_operator?, see sage.misc.decorator, or just look at
> this example:
>
> sage: @infix_operator('add')
> : def my_add(a,b):
> :     return (a[0]*b[0], a[1]+b[1])
> :
> sage: (3,"Hello") +my_add+ (4, "World!!")
> (12, 'HelloWorld!!')
>
> But it might make a lot more sense to make a simple class that prints
> out the string and number and has an operation defined on it.
>
> sage: class MyClass:
> :     def __init__(self, num, s):
> :         self._num=num
> :         self._s=s
> :     def __add__(self, other):
> :         if isinstance(other, MyClass):
> :             return MyClass(self._num*other._num, self._s+other._s)
> :         raise NotImplemented
> :     def __repr__(self):
> :         return str((self._num, self._s))
> :     def __str__(self):
> :         return self.__repr__()
> :
> sage: a=MyClass(3,"Hello")
> sage: b=MyClass(4,"World!!")
> sage: a
> (3, 'Hello')
> sage: b
> (4, 'World!!')
> sage: a+b
> (12, 'HelloWorld!!')
>
> Thanks,
>
> Jason

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[sage-devel] Bundle different objects

[Dox]

Hi people!

I was wondering if there is a way of bundle two kind of different
objects together and define operations on them.

Suppose, I'd like to bundle a number and a string (3, Hello) and (4,
World!!)... then define and operation which multiplies the numbers and
add strings, so the result is (12, HelloWorld!!)

Something like that!

Thank you all
;-)

Dox

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[sage-devel] Developing a General Relativity package

[Dox]

Hi everyone!

Nowadays I'm working in some complex supergravity calculations, so I'm
much involved into computing GR tensor (Riemann, Ricci and Einstein)
as well as Yang-Mills theories.

I'd like to help or start to develop a package for manipulate this
kind of symbolic manipulation.

How should I begin?

I've already got SAGE 4.6.1 src.

Regards!!!

Dox.

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[sage-devel] Possible bug in saving a plot!

[Dox]

Hi everyone,

Today I was writing a SAGE tip for my blog, about using customized
ticks in plots, and I realize that,

sage: p = plot(sin(x), (x, -7, 7), ticks=pi/2, tick_formatter=pi,
axes_labels=['$x$','$\\sin(x)$'], fontsize=14, color='red')

sage: p.save('/home/me/fig1.pdf')

sage: q = plot(2*x+1,(x,0,5),ticks=[[0,1,e,pi,sqrt(20)],
2],tick_formatter="latex")
sage: q.save('/home/me/fig2.pdf')

saves the figure but the customized ticks are not there, but the usual
numbering. Is this a bug?
I could save this only by showing the figure and save it from the
image viewer (I run Ubuntu 10.10).

An extra comment: Is it possible to write $\frac{3\pi}{2}#$ in the
ticks instead of $\frac{3}{2}\pi$ ? Just for the sake of compactness.

Thank you all!

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[sage-devel] Re: Transforming exponentials to hyperbolic functions.

[Dox]

Thank you very much Francois, much more explicit than I expected!!!

On Jan 23, 4:39 pm, Francois Maltey  wrote:
> Dox a crit :
>
> > Hi guys! I have an easy question... got an expression with
> > exponentials, say exp(x)+exp(-x), How can I get the result in terms of
> > hyperbolic functions
>
> 1/ First you can use the expr.subs method :
>
> y=exp(x)+exp(-x)
> y.subs(exp(x)==sinh(x)+cosh(x)).subs(exp(-x)=cosh(x)-sinh(x))
>
> [You must call subs for all subexpressions : exp(x) and (exp(-x)]
>
> 2/ Second you can also play with match, find and subs :
>
> w0=SR.wild(0)   # w0 is now a matching subexpression
> y.subs(exp(w0)==cosh(w0)+sinh(w0))
>
> The result is sinh(-x) + sinh(x) + cosh(-x) + cosh(x)
> And then y.subs(exp(w0)==cosh(w0)+sinh(w0)).simplify() is pretty.
>
> I think it's impossible to subs the function exp to the other (sum of)
> function(s) exp=cosh+sinh.
> You must use the regular subexpression SR.wild(0) [look at help about
> find, subs and match]
>
> 3/ Third, you can use the outside Sage function rewrite published 
> athttp://wiki.sagemath.org/symbolics/rewriteand get the attachement file
> rewrite.sage, load it.
> and call rewrite (y, rules="exp2sinhcosh").
>
> Choice what you prefer !
>
> F.

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[sage-devel] Transforming exponentials to hyperbolic functions.

[Dox]

Hi guys! I have an easy question... got an expression with
exponentials, say exp(x)+exp(-x), How can I get the result in terms of
hyperbolic functions?

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[sage-devel] Saving 3D plots

[Dox]

Hi guys!
I was wandering... Is it possible to choose the `angle of viewing' a
3D plot at the time of saving it?

Thank you.

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