On Wed, Sep 11, 2013 at 4:04 PM, <sympy@googlegroups.com> wrote: > Today's Topic Summary > > Group: http://groups.google.com/group/sympy/topics > > - pip install broken for python 3.3 <#1410c95d4814c66b_group_thread_0>[1 > Update] > - PyDy Visualization Milestone <#1410c95d4814c66b_group_thread_1> [1 > Update] > - Working on a different caching > approach.<#1410c95d4814c66b_group_thread_2>[1 Update] > - Divide by zero when transforming to > numerics<#1410c95d4814c66b_group_thread_3>[2 Updates] > - How to help sympy integrate > sqrt(a**2/(a**2-x**2))<#1410c95d4814c66b_group_thread_4>[1 Update] > - Status of the Diophantine Equation <#1410c95d4814c66b_group_thread_5>[1 > Update] > - How to apply a variational operator in > SymPy?<#1410c95d4814c66b_group_thread_6>[2 Updates] > > pip install broken for python > 3.3<http://groups.google.com/group/sympy/t/54cdf28883410884> > > Angus Griffith <16sn...@gmail.com> Sep 11 03:04AM -0700 > > Is there a workaround for this? > > I have a python2 application that depends on Sympy and I'm trying to > upgrade the dependency to 0.7.3. > > I've tried a few things but nothing successful yet. (Either the > package > isn't found or it tries (and consequently) fails to install the > python3 > version.) > > sympy==0.7.3, sympy-py2, sympy==0.7.3-py2 > > No local packages or download links found for ... > > > sympy>=0.7.3, sympy > > Best match: sympy 0.7.3-py3.3 > ... > > ImportError: You appear to be using the Python 3 version of SymPy in > Python > 2. Use Python 3 or get the Python 2 source code from http://sympy.org. > > > On Sunday, 28 July 2013 17:33:41 UTC+10, Matthew Brett wrote: > > > > PyDy Visualization > Milestone<http://groups.google.com/group/sympy/t/c76d1dd09c8d3331> > > Dale Lukas Peterson <hazelnu...@gmail.com> Sep 10 04:04PM -0700 > > > > http://youtu.be/W6MIwXUw7jQ > > > He's polishing up the code now and working on documentation. So we > should > > have a fully working 3D visualizer in a couple more weeks. > > That looks awesome! Great work. I'm very excited to try it out :) > > Luke > > > > -- > "People call me a perfectionist, but I'm not. I'm a rightist. I do > something until it's right, and then I move on to the next thing." > -- James Cameron > > > > Working on a different caching > approach.<http://groups.google.com/group/sympy/t/a275512a09aabd76> > > Gilbert Gede <gilbertg...@gmail.com> Sep 10 03:24PM -0700 > > Hi, > I've playing around with implementing a different caching strategy: > "user-level" functions within which the cache is enabled and after > which > the cache is cleared. I've opened a PR for the work in progress here: > https://github.com/sympy/sympy/pull/2448 > > I'm not sure if it's the best approach to a different caching > strategy, but > feel free to take a look and give some input/feedback. Or, > alternatively, > discuss if another strategy would be more appropriate for caching in > SymPy. > > -Gilbert > > > > Divide by zero when transforming to > numerics<http://groups.google.com/group/sympy/t/a1aa00229e033b14> > > Jason Moore <moorepa...@gmail.com> Sep 10 04:41PM -0400 > > I'll don't have a concrete example to show at the moment, but I feel > like > we get these singularity issues when we do use simplification and don't > when we don't or when we expand everything out. I'll try to put > together an > example where this is the case. > > > Jason > moorepants.info > +01 530-601-9791 > > > On Tue, Sep 10, 2013 at 4:14 PM, Stefan Krastanov < > stefan.krasta...@yale.edu > > > > > Jason Moore <moorepa...@gmail.com> Sep 10 04:43PM -0400 > > Also, why does .evalf give zero in my previous example? Shouldn't that > also > raise a DivideByZero error? > > > Jason > moorepants.info > +01 530-601-9791 > > > > > > How to help sympy integrate > sqrt(a**2/(a**2-x**2))<http://groups.google.com/group/sympy/t/307bb149e9a938c4> > > Aaron Meurer <asmeu...@gmail.com> Sep 09 12:05PM -0600 > > >> the heurisch or Meijer G algorithms. > > > Can the Meijer G be used to integrate any function, or is the the > most general > > algorithm still the Risch one? I read this: > > It depends on what you mean by "general". In my view, the two > algorithms handle different classes of integrals with different > advantages, and therefore they will both always be needed. > > Here's a list of facts for each algorithm > > # Meijer G > > Advantages: > > - Can handle a large class of special functions. > - Works particularly well with definite integrals (but it also can > compute indefinite integrals). > - Can compute convergence conditions for definite integrals > - Can split indefinite integrals into conditions as well (for > instance, integrate(1/sqrt(x**2 - 1), meijerg=True)). > > Disadvantages: > - Is only a heuristic, so while it is smarter than a basic table > lookup, it still requires some level of pattern matching. > - As with any such algorithm, it can be highly dependent on the form > of the expression. > - As such, won't recognize particularly complicated integrands. > - The indefinite integrator is not particularly strong, at least > compared to the definite one. > > # Risch > > Advantages: > > - Is a complete algorithm, so if an expression fits in the class it > recognizes (and the cases are all implemented), it will compute the > answer. > - Works with arbitrarily complicated expressions. > - Can prove that elementary integrals do not exist. > - Because the algorithm is complete, rather than relying on a pattern > matching heuristic, it doesn't rely on the form of the input > expression. It may end up changing the format of the output, but if an > answer exists, it will find one no matter what the input looks like > (unless the input is in some form that it hasn't been programmed to > recognize, e.g., currently Risch in SymPy doesn't handle hyperbolic > trig functions even though it could, because they are just > exponentials). > > Disadvantages: > > - Only works with a relatively small class of expressions (elementary > functions, plus there are some extensions for a few special > functions). > - Adding more cases requires quite a bit of work. > - Doesn't work for definite integrals directly. > > In general, Meijer G works well for a very large class of functions, > but not very complicated combinations of them, whereas Risch works > well for a small class of functions, but they can be arbitrarily > complex. That's why on the outset, Meijer G will seem to be more > powerful, because if you plug in every integral in an integration > table, it will catch more of them. But if you test the integrator in a > slightly different way, namely, by taking some random expression, > differentiating it, and passing it in, you'll have better luck with > the Risch algorithm (assuming the original expression was elementary). > > I didn't mention heurisch, but it falls somewhere in between. It still > uses pattern matching and can be highly sensitive to the form of the > input, but it's based on some of the theory of the Risch algorithm, so > it can work with reasonably complicated expressions, assuming the > answer looks like what it expects it to. It doesn't work so well with > special functions because it works best with functions whose > derivatives can be expressed in terms of itself. > > > > http://docs.sympy.org/dev/modules/integrals/g-functions.html > > > and it shows how to do the (0, oo) integrals, but not the general > > antiderivatives. > > Yes, it can do antiderivatives, and as I showed in that example above, > it can handle at least some algebraic functions. > > By the way, the best resource to find some formula, unless you have > one of those table books, is the Wolfram functions site. It's a little > hard to navigate, though (I wonder if you have a copy of Mathematica > if there is an easier way to do a table lookup within the software). > > > I found some formulas how to integrate G functions, but I don't know > if it is > > implemented in sympy. I.e. are there functions that cannot be > expressed > > using the G function? > > Tom or Raoul would have to give a more specific answer, but I believe > that there are functions that can't be expressed in terms of the > Meijer G-function. > > Aaron Meurer > > > > > Status of the Diophantine > Equation<http://groups.google.com/group/sympy/t/c5f6186ed3ffd070> > > Thilina Rathnayake <thilina.r...@gmail.com> Sep 09 10:30AM -0700 > > Hi Ondrej, > > I implemented solutions to the general sum of squares. That is to the > equations > of the form x_1**2 + x_2**2 + . . . + x_n**2 = k. I made a commit. > Please > take a > look at the following PR. The new function is named > `diop_general_sum_of_squares()` > and it's hooked to `diop_solve()` and `diophantine()`. > > https://github.com/sympy/sympy/pull/2432 > > Currently, the function returns only one solution and this is fast. > According to the > sources I referred, Finding all the solutions is exponential in `k` > and > closely related > to subset-sum problem. More than one solution can be found by using > `power_representation()` > described below but it's a brute and doesn't work for large `k`. > > I implemented a more general function which solves x_1**p + x_2**p + . > . . > + x_k**p = n > It is named as `power_represenatation()` and takes three arguments n, > k, > and p as in > above equation. I didn't hook it to the `diop_solve()` or > `diophantine()`. > I am doing a bit of > research on how I can improve this function. Even Wolfram Alpha > doesn't > have efficient solution > to this problem, for sufficiently large `n`, it gives a message saying > standard computation time exceeded. > > I implemented several functions like sum_of_three_squares() and > sum_of_four_squares() > which were needed to solve some of the Diophantine equations but these > functions naturally belong > under an Additive number theory module. Then, I can import these > functions > from it and use in the > Diophantine equation module. I expect to create an additive number > theory > module for SymPy but it will > be after I finish GSoC. > > I will start on the two issues you created from tomorrow. I was a bit > busy > during the last week since > I was stuck with university work, Hope to cover for that in this week. > > Regards, > Thilina. > > > > How to apply a variational operator in > SymPy?<http://groups.google.com/group/sympy/t/72f3a325d116a6b3> > > Saullo Castro <saullogiov...@gmail.com> Sep 09 03:31PM +0200 > > I've extended the: > > test_euler.py > > from Sergey's branch. > Unfortunately I did not manage to send him back a push request of the > performed changes, so I created a temporary gist here: > > https://gist.github.com/saullocastro/6495587 > > @Sergey, could you have a look if your module handles this type of > functionals. If not I want to put the ideas of this: > https://gist.github.com/saullocastro/6433919 > > Into your module. > > Thank you! > > > 2013/9/9 Aaron Meurer <asmeu...@gmail.com> > > > > > > Sergey B Kirpichev <skirpic...@gmail.com> Sep 09 07:36PM +0400 > > On Mon, Sep 09, 2013 at 03:31:50PM +0200, Saullo Castro wrote: > > Unfortunately I did not manage to send him back a push request of the > > performed changes > > Please, push your changes to some branch in your sympy's forked repo > on Github. Then navigate to your repository with the changes you want > someone else to pull. Select branch, and press the Pull Request > button, then new pull request. Choose my branch as base fork and > branch with your changes as head fork. > > Some guide is in our wiki: > > > https://github.com/sympy/sympy/wiki/Development-workflow#wiki-create-a-patch-file-or-pull-request-for-github > (Yet, a bit outdated pictures, I think.) > > > @Sergey, could you have a look if your module handles this type of > > functionals. > > It seems, your lagrangian has a high-order derivatives, like this: > > > http://en.wikipedia.org/wiki/Euler%E2%80%93Lagrange_equation#Single_function_of_single_variable_with_higher_derivatives > So, no. The pr#2431 is for classical mechanics (no constraints), just > a handy hard-coded formula. > > > > -- > You received this message because you are subscribed to the Google Groups > "sympy" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to sympy+unsubscr...@googlegroups.com. > To post to this group, send email to sympy@googlegroups.com. > Visit this group at http://groups.google.com/group/sympy. > For more options, visit https://groups.google.com/groups/opt_out. >
Hello, I am Elita Lobo. I am interested in contributing to the development of sympy. I want to participate in GSOC and work towards development of Sympy. I have a few project ideas related to the same. Can someone please guide me on how to get involved in Sympy development? -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sympy+unsubscr...@googlegroups.com. To post to this group, send email to sympy@googlegroups.com. Visit this group at http://groups.google.com/group/sympy. For more options, visit https://groups.google.com/groups/opt_out.
