Re: [sage-support] Re: What's wrong with sagenb ?

2012-10-29 Thread Christophe BAL
Happy to find one bug. [?] Christophe 2012/10/29 Jason Grout > On 10/29/12 2:41 PM, William Stein wrote: > >> On Mon, Oct 29, 2012 at 12:26 PM, Christophe BAL >> wrote: >> >>> Hello, >>> the following code takes more than one minute to acheive its job. >>> >>> Is there some technical problem w

[sage-support] Re: What's wrong with sagenb ?

2012-10-29 Thread Jason Grout
On 10/29/12 2:41 PM, William Stein wrote: On Mon, Oct 29, 2012 at 12:26 PM, Christophe BAL wrote: Hello, the following code takes more than one minute to acheive its job. Is there some technical problem with the server ? Yes, it doesn't know French. Get rid of the e with the accent over it

Re: [sage-support] What's wrong with sagenb ?

2012-10-29 Thread William Stein
On Mon, Oct 29, 2012 at 12:26 PM, Christophe BAL wrote: > Hello, > the following code takes more than one minute to acheive its job. > > Is there some technical problem with the server ? Yes, it doesn't know French. Get rid of the e with the accent over it in : print "Nombre de divisi

[sage-support] What's wrong with sagenb ?

2012-10-29 Thread Christophe BAL
Hello, the following code takes more than one minute to acheive its job. Is there some technical problem with the server ? Christophe Simple code = def pgcdBoucle(a, b): n = 0 if b > a: a, b = b, a while(b != 0): a, b = b, a%b n += 1 return (

[sage-support] Cholesky for sparse matrix

2012-10-29 Thread Raniere Gaia Silva
Hi, I need to performe a (numerical) cholesky factorization of a sparse matrix (20x20) but I'm getting a error. I look at this thread https://groups.google.com/forum/?fromgroups=#!searchin/sage-devel/cholesky/sage-devel/AW4pmKx49H4/7iuet3rWYQgJ but it didn't help very much (and is a little old). B

Re: [sage-support] Re: Strange results in DiGraph.girth()

2012-10-29 Thread Georgi Guninski
On Mon, Oct 29, 2012 at 01:29:43PM +0100, Nathann Cohen wrote: > > May be you are right. Powers of the matrix appear easier to implement > > IMHO. After some reading I don't think you can do better than > > O(n^(3-epsilon)) because of odd cycles. > > Ahahaahah. Well, implement the Matrix version a

Re: [sage-support] Re: Strange results in DiGraph.girth()

2012-10-29 Thread Nathann Cohen
> May be you are right. Powers of the matrix appear easier to implement > IMHO. After some reading I don't think you can do better than > O(n^(3-epsilon)) because of odd cycles. Ahahaahah. Well, implement the Matrix version and I will implement the graph thing. We could be checking the results ins

Re: [sage-support] Re: Strange results in DiGraph.girth()

2012-10-29 Thread Georgi Guninski
On Mon, Oct 29, 2012 at 02:35:47AM -0700, P Purkayastha wrote: > > I wonder if it is less computationally demanding to walk around the graph > than take powers of M, especially for large, but sparsely connected graphs. > May be you are right. Powers of the matrix appear easier to implement IMHO.

Re: [sage-support] Re: Strange results in DiGraph.girth()

2012-10-29 Thread P Purkayastha
On Monday, October 29, 2012 2:59:43 PM UTC+8, Georgi Guninski wrote: > > On Sun, Oct 28, 2012 at 07:17:59AM -0700, Nathann Cohen wrote: > > > > > > > Well, the documentation says > > > "Computes the girth of the graph. For directed graphs, computes the > > > girth of the undirected graph."