Mailman 3 July 2009 - SciPy-Dev

Weird problem trying to preview Milestones edit
by David Goldsmith July 6, 2009

July 6, 2009

Hi! Editing the Milestones page, if I try to preview (even before I make any edits), I get: * Wiki * Docstrings * Changes * Milestones * Search * Stats * Patch * — * Log in 500 Internal Error even on multiple refreshes. I don't get this previewing edits on any other page (so far), and it's the first time it's happened to me while editing Milestones (which I've successfully edited several times). Is that a sign that it's locked 'cause someone else is editing it simultaneously? Otherwise, something's amiss. DG

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Re: [SciPy-dev] Weird problem trying to preview Milestones edit
by David Goldsmith July 6, 2009

July 6, 2009

Thanks for confirming. DG --- On Sun, 7/5/09, Scott Sinclair <scott.sinclair.za(a)gmail.com> wrote: > From: Scott Sinclair <scott.sinclair.za(a)gmail.com> > Subject: Re: [SciPy-dev] Weird problem trying to preview Milestones edit > To: "SciPy Developers List" <scipy-dev(a)scipy.org> > Date: Sunday, July 5, 2009, 11:33 PM > >2009/7/6 David Goldsmith <d_l_goldsmith(a)yahoo.com>: > > > > Hi! Editing the Milestones page, if I try to preview > (even before I make any edits), I get: > > > > * Wiki > > * Docstrings > > * Changes > > * Milestones > > * Search > > * Stats > > * Patch > > * — > > * Log in > > > > 500 Internal Error > > > > even on multiple refreshes. I don't get this > previewing edits on any other page (so far), and it's the > first time it's happened to me while editing Milestones > (which I've successfully edited several times). > > > > I'm seeing this too. No problems on other pages. > > Cheers, > Scott > _______________________________________________ > Scipy-dev mailing list > Scipy-dev(a)scipy.org > http://mail.scipy.org/mailman/listinfo/scipy-dev >

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Re: [SciPy-dev] Example of eig not converging
by David Goldsmith July 3, 2009

July 3, 2009

Thanks, Pauli. In that case, I won't worry about it (I thought there was some "well-known" condition, like w/ the condition number and numerical invertibility, but if not, then there's no point in illustrating it w/ an example). DG --- On Fri, 7/3/09, Pauli Virtanen <pav(a)iki.fi> wrote: > From: Pauli Virtanen <pav(a)iki.fi> > Subject: Re: [SciPy-dev] Example of eig not converging > To: scipy-dev(a)scipy.org > Date: Friday, July 3, 2009, 11:38 AM > On 2009-07-03, David Goldsmith <d_l_goldsmith(a)yahoo.com> > wrote: > > What has to be true of `a` so that eig(a) fails to > converge? > > The approximate answer is: in practice, it always > converges. > > Mathematically, the eigenvalue problem of an n x n matrix > is > well-defined (modulo floating-point accuracy). So the > actual > answer is very much implementation-dependent. LAPACK is a > widely > used library, and I suppose its eigenvalue routines are > quite > robust. So, failing matrices are probably difficult to > find, and > constructing them probably requires looking carefully at > the > algorithm itself, unless LAPACK authors themselves have > listed > some examples somewhere. (I didn't find any with a quick > search.) > > So, I don't know the answer, and I suppose it would take > quite a > bit of work to find out. > > -- > Pauli Virtanen > > _______________________________________________ > Scipy-dev mailing list > Scipy-dev(a)scipy.org > http://mail.scipy.org/mailman/listinfo/scipy-dev >

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Example of eig not converging
by David Goldsmith July 3, 2009

July 3, 2009

What has to be true of `a` so that eig(a) fails to converge? DG

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Re: [SciPy-dev] Summer Marathon "Category of the Week"
by David Goldsmith July 3, 2009

July 3, 2009

eig = done! DG --- On Thu, 7/2/09, Stéfan van der Walt <stefan(a)sun.ac.za> wrote: > From: Stéfan van der Walt <stefan(a)sun.ac.za> > Subject: Re: [SciPy-dev] Summer Marathon "Category of the Week" > To: "SciPy Developers List" <scipy-dev(a)scipy.org> > Date: Thursday, July 2, 2009, 3:20 AM > Hi marathon runners, > > Well done on the progress made last week! > > 2009/7/1 David Goldsmith <d_l_goldsmith(a)yahoo.com>: > > Linear Algebra! (My favorite! :-)) Let's get it to > pink or better by next Wed! > > Excellent! The linalg module is shown here: > > http://docs.scipy.org/numpy/docs/numpy.linalg/ > > You can choose from: > > cholesky cond det eig eigh eigvals eigvalsh > inv lstsq matrix_power norm inv qr solve svd tensorinv > tensorsolve > > These mostly have decent docstrings already, so I'd suggest > focusing > on making the following more accessible to your typical > linear algebra > student: > > http://docs.scipy.org/numpy/docs/numpy.linalg.linalg.eig/ > [1] > http://docs.scipy.org/numpy/docs/numpy.linalg.linalg.qr/ > [2] > http://docs.scipy.org/numpy/docs/numpy.linalg.linalg.norm/ > [3] > http://docs.scipy.org/numpy/docs/numpy.linalg.linalg.svd/ > [4] > http://docs.scipy.org/numpy/docs/numpy.linalg.linalg.tensorinv/ > [5] > > Have fun! > Stéfan > > [1] In the notes section, describe right vs left > eigenvectors. > Personally, I think we can drop the reference to the > characteristic > polynomial (we > don't solve it that way in any case). > > [2] Needs formatting and a link to an explanation of QR. > > [3] Describe what Frobenius means, or give a link to an > appropriate reference. > > [4] Note Pauli's comment: indicate clearly that the > decomposition A = > U S V.T is returned (V.H for complex matrices). > > [5] Badly in need of some examples. > _______________________________________________ > Scipy-dev mailing list > Scipy-dev(a)scipy.org > http://mail.scipy.org/mailman/listinfo/scipy-dev >

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Re: [SciPy-dev] Is this a (formatting) bug?
by David Goldsmith July 3, 2009

July 3, 2009

I figured out a "work-around": >>> w,v=LA.eig(np.diag((1,2,3))) >>> w;v array([ 1., 2., 3.]) array([[ 1., 0., 0.], [ 0., 1., 0.], [ 0., 0., 1.]]) But I'm still "concerned" about how >>> w,v (effectively) is printed (though I now see more clearly that it's an artifact of how a tuple is printed, not an artifact of how LA.eig is printed, and thus probably "unfixable" solely within numpy). DG --- On Thu, 7/2/09, David Goldsmith <d_l_goldsmith(a)yahoo.com> wrote: > From: David Goldsmith <d_l_goldsmith(a)yahoo.com> > Subject: [SciPy-dev] Is this a (formatting) bug? > To: scipy-dev(a)scipy.org > Date: Thursday, July 2, 2009, 10:08 PM > > Actual output: > > >>> from numpy import linalg as LA > >>> LA.eig(np.diag((1,2,3))) > (array([ 1., 2., 3.]), array([[ 1., > 0., 0.], > [ 0., 1., 0.], > [ 0., 0., > 1.]])) > > i.e., a line feed wasn't inserted between w and v. > > Bug? > > DG > > > > _______________________________________________ > Scipy-dev mailing list > Scipy-dev(a)scipy.org > http://mail.scipy.org/mailman/listinfo/scipy-dev >

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Is this a (formatting) bug?
by David Goldsmith July 3, 2009

July 3, 2009

Actual output: >>> from numpy import linalg as LA >>> LA.eig(np.diag((1,2,3))) (array([ 1., 2., 3.]), array([[ 1., 0., 0.], [ 0., 1., 0.], [ 0., 0., 1.]])) i.e., a line feed wasn't inserted between w and v. Bug? DG

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Re: [SciPy-dev] Summer Marathon "Category of the Week"
by David Goldsmith July 2, 2009

July 2, 2009

OK, the gauntlet has been thrown: anyone have the time and expertise to commit to fixing this code (I can commit to fixing the docstring) this week? DG --- On Thu, 7/2/09, Stéfan van der Walt <stefan(a)sun.ac.za> wrote: > From: Stéfan van der Walt <stefan(a)sun.ac.za> > Subject: Re: [SciPy-dev] Summer Marathon "Category of the Week" > To: "SciPy Developers List" <scipy-dev(a)scipy.org> > Date: Thursday, July 2, 2009, 4:16 AM > 2009/7/2 Nils Wagner <nwagner(a)iam.uni-stuttgart.de>: > > Is there a chance to fix the following ticket > > http://projects.scipy.org/numpy/ticket/937 > > in this context ? > > Sure, I'd gladly review any patches (I'm a bit swamped > myself at the moment). > > Regards > Stéfan > _______________________________________________ > Scipy-dev mailing list > Scipy-dev(a)scipy.org > http://mail.scipy.org/mailman/listinfo/scipy-dev >

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Summer Marathon "Category of the Week"
by David Goldsmith July 2, 2009

July 2, 2009

Linear Algebra! (My favorite! :-)) Let's get it to pink or better by next Wed! DG

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Tutorial topics for SciPy'09 Conference
by Fernando Perez July 1, 2009

July 1, 2009

Hi all, The time for the Scipy'09 conference is rapidly approaching, and we would like to both announce the plan for tutorials and solicit feedback from everyone on topics of interest. Broadly speaking, the plan is something along the lines of what we had last year: one continuous 2-day tutorial aimed at introductory users, starting from the very basics, and in parallel a set of 'advanced' tutorials, consisting of a series of 2-hour sessions on specific topics. We will request that the presenters for the advanced tutorials keep the 'tutorial' word very much in mind, so that the sessions really contain hands-on learning work and not simply a 2-hour long slide presentation. We will thus require that all the tutorials will be based on tools that the attendees can install at least 2 weeks in advance on all platforms (no "I released it last night" software). With that in mind, we'd like feedback from all of you on possible topics for the advanced tutorials. We have space for 8 slots total, and here are in no particular order some possible topics. At this point there are no guarantees yet that we can get presentations for these, but we'd like to establish a first list of preferred topics to try and secure the presentations as soon as possible. This is simply a list of candiate topics that various people have informally suggested so far: - Mayavi/TVTK - Advanced topics in matplotlib - Statistics with Scipy - The TimeSeries scikit - Designing scientific interfaces with Traits - Advanced numpy - Sparse Linear Algebra with Scipy - Structured and record arrays in numpy - Cython - Sage - general tutorial - Sage - specific topics, suggestions welcome - Using GPUs with PyCUDA - Testing strategies for scientific codes - Parallel processing and mpi4py - Graph theory with Networkx - Design patterns for efficient iterator-based scientific codes. - Symbolic computing with sympy We'd like to hear from any ideas on other possible topics of interest, and we'll then run a doodle poll to gather quantitative feedback with the final list of candidates. Many thanks, f

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