Re: [sage-devel] Re: Interested in co-writing an article?
Le 12/10/2014 06:12, rjf a écrit : On Friday, October 10, 2014 6:26:24 PM UTC-7, Alasdair wrote: I've written an article about using Sage to develop explicit Runge-Kutta formulas for the numerical solution of ODEs. Since the use of a computer algebra system to develop explicit R-K formulas is pretty much of a classic operation, and can be done by Maxima which is open source, and in fact seems to be done by Maxima in your paper, with a gloss of Sage on top, it is not clear that you have something new to contribute. Besides, high-order RK methods are, as I recall, not very appealing in practice. This is a genuinely false assertion: in celestial mechanics people use implicit (Gaussian) RK method of order 16! But ok, I dont think this is the place to discuss this... -- You received this message because you are subscribed to the Google Groups sage-devel group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at http://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout. attachment: tdumont.vcf
Re: [sage-devel] Re: Posets and lattices, location of functions
Hello ! True; also for example there could be doublehasse, i.e. structure with both upper and lower covers saved as a list for an element. Isn't that already the case ? A hasse digram should be a (sparse) digraph, and a (sparse) digraph should be stored twice internally, once for in-neighborhood and one for out-neighborhood. Did you find the in-neighbors method too slow somewhere ? We had a problem like that at some point. Nathann -- You received this message because you are subscribed to the Google Groups sage-devel group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at http://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
Re: [sage-devel] Re: Posets and lattices, location of functions
On Sun, 12 Oct 2014, Nathann Cohen wrote: True; also for example there could be doublehasse, i.e. structure with both upper and lower covers saved as a list for an element. Isn't that already the case ? A hasse digram should be a (sparse) digraph, and a (sparse) digraph should be stored twice internally, once for in-neighborhood and one for out-neighborhood. I don't know. Where should the code for that be? Your implementation of static sparce graph is so fast that I don't know if there is any significant difference at all. Did you find the in-neighbors method too slow somewhere ? We had a problem like that at some point. Not a real problem. At http://trac.sagemath.org/ticket/13223 Darij Grinberg writes I've improved the situation in #13240; the algorithm is now polynomial time. Wouldn't hurt to improve it nevertheless. Actually algorithm is linear already. I was just thinking what he have had in mind when writing that; there doesn't seem to be significantly better algorithm. -- Jori Mäntysalo -- You received this message because you are subscribed to the Google Groups sage-devel group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at http://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
Re: [sage-devel] Re: Posets and lattices, location of functions
Yo ! I don't know. Where should the code for that be? sage: d = DiGraph() sage: d._backend class 'sage.graphs.base.sparse_graph.SparseGraphBackend' sage: b=d._backend sage: b.iterator_in_nbrs?? Your implementation of static sparce graph is so fast that I don't know if there is any significant difference at all. Usually all the time is wasted translating arbitrarily labelled vertices into ints. Not a real problem. At http://trac.sagemath.org/ticket/13223 Darij Grinberg writes I've improved the situation in #13240; the algorithm is now polynomial time. Wouldn't hurt to improve it nevertheless. Actually algorithm is linear already. I was just thinking what he have had in mind when writing that; there doesn't seem to be significantly better algorithm. Oh. Well, you can send him an email. I will take a lot at it right now, however. I have a lot of work to do, and you give me an occasion to not touch it. Nathann -- You received this message because you are subscribed to the Google Groups sage-devel group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at http://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
[sage-devel] fail to make
Hello, I got that on two different machines with 6.4.beta5: Error building Sage. The following package(s) may have failed to build: package: python-2.7.8 Does anybody else meet the same problem ? I have not yet used the heavy option make distclean, because I hate to recompile ATLAS Frederic -- You received this message because you are subscribed to the Google Groups sage-devel group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at http://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
Re: [sage-devel] fail to make
On 2014-10-12 20:47, Frédéric Chapoton wrote: Hello, I got that on two different machines with 6.4.beta5: Error building Sage. The following package(s) may have failed to build: package: python-2.7.8 Log file please... -- You received this message because you are subscribed to the Google Groups sage-devel group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at http://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
[sage-devel] Re: fail to make
Well, the log file is rather huge (10.6 M). Here is just the failing part: make[3]: Leaving directory `/homes/doua/chapoton/sage/local/var/tmp/sage/build/\ python-2.7.8/src' Installing valgrind suppression file... cp: cannot create regular file '/homes/doua/chapoton/sage/local/share/sage/ext/\ valgrind/python.supp': No such file or directory Error installing valgrind suppression file. real21m7.321s user3m50.989s sys 0m49.290s Error installing package python-2.7.8 Le dimanche 12 octobre 2014 20:47:02 UTC+2, Frédéric Chapoton a écrit : Hello, I got that on two different machines with 6.4.beta5: Error building Sage. The following package(s) may have failed to build: package: python-2.7.8 Does anybody else meet the same problem ? I have not yet used the heavy option make distclean, because I hate to recompile ATLAS Frederic -- You received this message because you are subscribed to the Google Groups sage-devel group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at http://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
Re: [sage-devel] Re: fail to make
On 2014-10-12 21:25, Frédéric Chapoton wrote: Well, the log file is rather huge (10.6 M). Here is just the failing part: make[3]: Leaving directory `/homes/doua/chapoton/sage/local/var/tmp/sage/build/\ python-2.7.8/src' Installing valgrind suppression file... cp: cannot create regular file '/homes/doua/chapoton/sage/local/share/sage/ext/\ valgrind/python.supp': No such file or directory Error installing valgrind suppression file. Fixed in http://trac.sagemath.org/ticket/17139 needs review. -- You received this message because you are subscribed to the Google Groups sage-devel group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at http://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
[sage-devel] Re: fail to make
Workaround:
mkdir -p local/share/sage/ext/valgrind
make
On Sunday, October 12, 2014 8:25:46 PM UTC+1, Frédéric Chapoton wrote:
Well, the log file is rather huge (10.6 M).
Here is just the failing part:
make[3]: Leaving directory
`/homes/doua/chapoton/sage/local/var/tmp/sage/build/\
python-2.7.8/src'
Installing valgrind suppression file...
cp: cannot create regular file
'/homes/doua/chapoton/sage/local/share/sage/ext/\
valgrind/python.supp': No such file or directory
Error installing valgrind suppression file.
real21m7.321s
user3m50.989s
sys 0m49.290s
Error installing package python-2.7.8
Le dimanche 12 octobre 2014 20:47:02 UTC+2, Frédéric Chapoton a écrit :
Hello,
I got that on two different machines with 6.4.beta5:
Error building Sage.
The following package(s) may have failed to build:
package: python-2.7.8
Does anybody else meet the same problem ?
I have not yet used the heavy option make distclean, because I hate to
recompile ATLAS
Frederic
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[sage-devel] Graphic Model Hierarchy Tools and Methods
Write this and send to mail lists for Graphviz, igraph, graph-tool and networkx. I am looking for a way to better represent models of systems. I currently use Visio. It is failing my needs for multiple reasons. Some of the specific failures a programmable tool may alleviate may be: Life-cycle change management – Track what changes through the system life cycle development process. Hierarchal relationship management – During development, the system starts out as a block diagram, a single block. This is broken down into high level functional blocks. These blocks will undergo further decomposition/refinement. Each refinement is one of many that can be realized. Alternatives are evaluated and eventually selected. Keeping track of these in Visio requires tracking/cataloguing files and their relationships – not an intuitive task. With the associated network for each of these block diagrams, I am guessing there should be a method to store the data along with relationships. These systems start off with the single system block. They refine to 200 to 5,000 components (nodes) and 5,000 to 20,000 connections (edges). This is probably the greatest advantage of programmable solutions: The ability to present/render layouts to accommodate viewpoints of a variety of stakeholders. What are the concepts, tools, modules and methods that would help me achieve these goals? I am looking for info that will help me come up to speed efficiently. Rayj -- You received this message because you are subscribed to the Google Groups sage-devel group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at http://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
[sage-devel] (fwd from sage-support) A mathematical mistake in root_lattice_realizations.py
Hi Dinakar, It makes more sense to post it on sage-devel as it concerns Sage development and not a question you have about Sage. So I did the forward. Vincent -- Forwarded message -- From: Dinakar Muthiah dmuth...@gmail.com Date: Sun, 12 Oct 2014 11:51:56 -0700 (PDT) Subject: [sage-support] A mathematical mistake in root_lattice_realizations.py To: sage-supp...@googlegroups.com I claim there is currently a mathematical mistake in the way the is_real_root method in the file root_lattice_realizations.py is implemented. There is also a parallel mistake in is_imaginary_root. Let me illustrate with an example: sage: R = RootSystem([A,2,1]).weight_lattice() sage: alpha = R.simple_roots() sage: alpha[0].is_real_root() True sage: b = 2*alpha[0] sage: b.is_real_root() True b.is_real_root() should return false because 2*alpha[0] is not a real root. In particular, 2*alpha[0] is not a root. Looking at the implementation of is_real_root(), it is easy to see why this isn't working properly. def is_real_root(self): r Return ``True`` if ``self`` is a real root. A root `\alpha` is real if it is `W` conjugate to a simple root where `W` is the corresponding Weyl group. EXAMPLES:: sage: Q = RootSystem(['B',2,1]).root_lattice() sage: alpha = Q.simple_roots() sage: alpha[0].is_real_root() True sage: elt = alpha[0] + alpha[1] + 2*alpha[2] sage: elt.is_real_root() False return self.norm_squared() 0 self.norm_squared() is not the way to check whether an element of the root space or weight_space is a real root. The problem is that there is no check to see whether self is a root. In affine types, the following should work: return (self.norm_squared() 0) and self.is_root() where is_root() would be a method that checks whether self is a root. But this isn't currently implemented, and I don't know what would be the most intelligent way to implement this. In affine types, this is fairly straight forward assuming you have a test for checking whether something is a root in the finite root system, but I don't know for general Cartan types. What do people think about this? I have not contributed to sage in the past, but I am interested in implementing the fix. Also, is there a better place for me to post this bug. I looked here: http://wiki.sagemath.org/support/ReportingBugs, and it suggested I post on sage-support since I don't have experience developing sage or using trac. Best, Dinakar -- You received this message because you are subscribed to the Google Groups sage-devel group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at http://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
