Harald Schilly

Sorting is Linear - also in Go!

2011-07-01T16:16:00.003+02:00

Wrttien in Go

package main

/*
   Sorting a list of positive int64 values is linear, also in Go!
   Author: Harald Schilly 
   Based on some bash script I found somewhere on the internetz ...
*/

import "time"

func main() {
  var vals = []int64 { 55, 1, 9, 0, 31, 11, 90, 11 }

  var ret  = make(chan int64)
  var done = make(chan bool)

  // main loop, just a single for loop
  for _, v := range vals {
    go func(v int64) {
      // if it doesn't sort well, increase the 1e5
      time.Sleep(1e5 * v)
      ret <- v
    } (v)
  }

  // output iterates over all results in the ret channel
  go func() {
    for i := 0; i < len(vals); i++ {
      println(<-ret)
    }
    done <- true
  }()

  <-done
}

Java XML DOM Document creation

2010-11-12T20:34:00.000+01:00

/**
* Since if found some crap on the Internet, here a better example for creating an XML document in Java.
*
* Copyright: Harald Schilly
* License: Apache 2.0
*/

package at.schilly.aldap2.ue12131415xml;

import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Map;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;

/** @author harald schilly */
public class MapToXml {

  final private SimpleDateFormat dateformat = new SimpleDateFormat("yyyy-MM-dd");

  /** this method takes a Map of Strings to Strings and builds an xml document.
   *
   * @param xmlfn
   * xml output filename
   * @param map
   * just a plain Map
   * @throws ParserConfigurationException
   * @throws FileNotFoundException
   * @throws TransformerException */
  public void write(final File xmlfn, final Map map)
   throws ParserConfigurationException, FileNotFoundException,
   TransformerException {
   // Docbuilder to create the xmldoc
   DocumentBuilderFactory docbuilderfactory = DocumentBuilderFactory.newInstance();
   DocumentBuilder docbuilder = docbuilderfactory.newDocumentBuilder();
   Document xmldoc = docbuilder.newDocument();

   // That's the root element
   Element root = xmldoc.createElement("map");

   // last saved element
   Element lastsaved = xmldoc.createElement("lastSavedBy");
   lastsaved.setAttribute("name", "Harald Schilly");
   lastsaved.setAttribute("date",
   dateformat.format(Calendar.getInstance().getTime()));
   root.appendChild(lastsaved);

   // iterate over map and add the entry/value elements
   for (Map.Entry mapentry : map.entrySet()) {
   Element entry = xmldoc.createElement("entry");
   entry.setAttribute("key", mapentry.getKey());

   Element value = xmldoc.createElement("value");
   Node node = xmldoc.createTextNode(mapentry.getValue());

   value.appendChild(node);
   entry.appendChild(value);
   root.appendChild(entry);
   }
   xmldoc.appendChild(root);

   // get a transformer with the given .dtd
   TransformerFactory transormerfactory = TransformerFactory.newInstance();
   Transformer transformer = transormerfactory.newTransformer();
   transformer.setOutputProperty(OutputKeys.DOCTYPE_SYSTEM, "map.dtd");
   transformer.setOutputProperty(OutputKeys.ENCODING, "UTF-8");
   transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "no");
   transformer.setOutputProperty(OutputKeys.INDENT, "yes");

   // transform and write to a file
   // use a StringWriter() object to write to a string.
   FileOutputStream fos = new FileOutputStream(xmlfn);
   BufferedOutputStream bos = new BufferedOutputStream(fos);
   StreamResult result = new StreamResult(bos);
   DOMSource source = new DOMSource(xmldoc);
   transformer.transform(source, result);
  }
}

Anchors in Sage Notebooks

2010-03-06T19:18:00.004+01:00

If you have a lengthy Sage Notebook and you want to quickly jump to a certain header or paragraph as a reference, use HTML anchors. They work like follows:

An <a name="anchorname"></a> tag must be inserted at the position you want to jump to.
Reference it via <a href="#anchorname">some text</a>.

After that, you can jump to the marked position just by clicking on the some text link.

To insert rich text and HTML, use the rich text editor accessible via <shift>+<click on blue insert bar>. There is an "HTML" icon. Alternatively, you can use the html() function:
i.e. html('<a name="test"></a>') ...

dotA Itemkauf Optimierung

2010-02-13T22:08:00.004+01:00

Mein Mitbewohner ließ nicht locker,
spielte täglich dieses dotA.

Nach jedem Itemkauf fragte er sich,
ob sich das nicht besser machen lies.

Hier ein ZIMPL Skript zum optimieren,
bitte schreib es fertig, sonst ists zum genieren.

Flott sagt dir SCIP dann ganz korrekt,
wo du am besten dein Gold hinsteckst.

# zimpl model for optimizing buying dotA items
# copyright 2010: harald schilly
# license: CC-BY-NC-SA 3.0

# helden
set helden := { 1 to 5 };

# freie plätze zum einkaufen
param frei[helden] := <1> 6, <2> 4, <3> 4, <4> 2, <5> 6;

# welche items es gibt
set items := { 1 to 3} ;

# kosten pro item
param itemcost[items] := <1> 100, <2> 50, <3> 63;

# menge der fähigkeiten die jeder item pushen kann
set abilities := { 1 to 4 };

# was jeweils besser wird
param itempower[abilities * items] :=
  | 1, 2, 3 |
|1| 5, 1, 0 |
|2| 0, 1, 4 |
|3| 1, 1, 8 |
|4| 1, 4, 10 |;

# basiswert der zum maximum einer spalte addiert wird
# notwendig in der zielfunktion für die gewichtung
param baseval := 1;

# gesamtbuget an gold
param budget := 500;

# die variablenmatrix
var buy[helden * items] integer >= 0 <= 6;

# man kann nur so viel kaufen wie geld da ist
subto costs:
  sum <h,i> in helden * items:
   buy[h,i] * itemcost[i] <= budget;

# man kann nur so viel kaufen wie der
# held noch freie plätze hat
subto maxperheld:
  forall in helden:
   sum in items: buy[h, i] <= frei[h];

# ich will die fähigkeiten meines teams maximieren
maximize obj: sum <h,i,a> in helden * items * abilities:
  (itempower[a, i] / (baseval + max <a> in abilities: itempower[a,i])) * buy[h, i];

Compiling Sage on my Atom N270 Netbook

2010-01-21T20:06:00.008+01:00

Here are some notes to myself regarding compiling Sage on my HP Mini 2140 with an Atom N270 CPU. I'm running Linux Ubuntu 9.10. This successfully compiles Sage 4.3 and 4.3.1 and might also work for later version.

Download

# using aria2, first get aria2
$ sudo apt-get install aria2

# go to a local directory and just use the .metalink link
$ aria2c http://server/path/sage-x.y.z.tar.metalink

# note, that aria2c doesn't stop when it has finished.
# it will start seeding the file to others via bittorrent.
# You can terminate this by hitting Ctrl-C

####

# or download via http/ftp from the download page

Verify

# If you think your download might have been corrupted, verify it:
$ aria2c -V http://server/path/sage-x.y.z.tar.metalink

Extract

# any local directory is fine

$ tar xf sage-x.y.z.tar

Prerequisites

# You need some tools to compile Sage:

$ sudo apt-get install build-essential m4\
readline libreadline-dev gfortran texlive

# read more: Installation Guide

Setup Build Environment

$ cd sage-x.y.z

# get rid of some environment variables, unless
# you know what you do (i.e. ccache, ...)
$ unset CC
$ unset CXX

# see README.txt if you need this
$ export SAGE_FAT_BINARY="yes"

# if you have gfortran library problems
# find your correct paths via $ locate gfortran

# setting these variables is necessary on Ubuntu 9.10
$ export SAGE_FORTRAN=/usr/bin/gfortran
$ export SAGE_FORTRAN_LIB=/usr/lib/libgfortran.so.3
# note: do not start over compilation if that problem happens,

# you have to remove and clean up everything first

# there are two cores in the CPU

# use both of them in parallel!
$ export MAKE="make -j2"

Start Compilation

# in a resource friendly mode

$ ionice -c 3 nice make

Testing and Packaging

If compilation didn't end with an error (otherwise: search, sage-support and sage-devel or irc chat)

# Test the entire beast (2 for 2 CPU cores):

$ ./sage -tp 2 devel/sage-main
# or
$ ./sage -testall
# once again, please report problems

If you want to build a binary distribution, upload it to us at sagemath.org or send it to a friend with a similar machine+system:

$ ./sage -bdist x.y.z-LinuxVersion;

On systems like Ubuntu, you can shrink the resulting archive much smaller using lzma compression. "trans-compress" it via:

$ zcat sage-x.y.z-...tar.gz | lzma -zv > sage-x.y.z-...tar.lzma

and to extract the tar.lzma later:

$ tar --lzma -xvf sage-x.y.z...tar.lzma

Links

Maintaining a Mirror Network

2009-11-29T18:58:00.000+01:00

Here are some notes about maintaining a mirror network. I'm talking about the Sage software, which is a nice open source mathematics program. Besides the source, there are many prebuilt binaries for various platforms. In total, for each release once a month, there have to move about 14GB in 27 files to 18 mirror websites on all continents of the world. It's important to have nearby mirrors, because the network connectivity might be weak in some areas. In Nov. 2009, the virtual box image for windows alone generated about 1.5 TB of traffic - all other binaries and source combined probably also 1.5 TB. Therefore, the mirror networks net efficiency is approximately a tenfold increases of the outgoing data volume.

To ensure that only those mirrors which are online and up-to-date are listed on the website, a small Python script checks a time-stamp file with a content-specific checksum. Only if it is correct and retrievable, the mirror is included. This check happens every 10 minutes, using Linux's cron mechanism.

Recently I enhanced this to visualize how the mirrors perform over time. This is especially interesting when a new release is mirrored out into the world. To see how this looks like, here is the graphic for the Sage 4.2.1 rollout:

Time starts at the bottom, you see it's around 14:00 GMT on Nov. 17th. The first working mirror is "UW", which is the master. The master mirror is excluded, once there is at least another one in North America online - as you can see that's SFU and Boston (Harvard). You can also see that it takes more than one day to sync with the mirrors. Besides that the transfer takes its time, they are probably scheduled to start sync only once a day, the master mirror rejects too many simultaneous connections, too many users download directly from the main server or there is simply some other timeout! Why are there two breaks? Well, not all binaries are ready at the same time and the timestamp is for the whole mirror, so that you do not access an outdated mirror. The broken line of Yandex is also a bit odd, but that's because they have multiple servers and seem to switch between.

How does it look right now? Here is the website for the mirror log visualization. There is also a link to how it looked last week.

Beyond just retrieving a file through http or ftp you can use a metalink file. Through a client it enables downloading from all available mirrors simultaneously and the client selects a few but fastest mirrors automatically. It also checks consistency and downloads are resumable. That's the ideal solution if you have a weaker connection and need to stop a huge transfer for some time or it is just flaky. Hint: use aria2 or DownThemAll.

Ok, at last some words about hosting a mirror. Two things are important: sync often to avoid wasting time when you could transfer data, but only sync once at a time ;) I've written how i did set up a mirror (the Boston one) in a MirrorNetwork wiki page.

In case the main website is down, you can find a mirror here.

Thank's to all our mirror hosters! Without them Sage would probably never reach their users and new mirrors are always welcome, especially in southern asia!

Popularity of Sage

2009-08-11T19:11:00.015+02:00

This post is about Sage download statistics.

I try to track the actual download events and derive some information about them. This post is about the timerange June 1st until Aug 12th (today). The basic numbers are, that Sage is downloaded most often in the USA (35%), followed by Germany (7%), France (5%), UK, Italy, Spain, Canada, China, Brazil and Japan (4 to 2 %). On average, Sage was downloaded 150 times each day during the last semester, and a bit more than 100 times during summer break. I hope, numbers will go up again ;)

But that's rather boring and I tried to put the numbers in context. I focused on those countries with more than one million inhabitants and scaled the download numbers with the population size or with the number of internet users. To my surprise, the hit-list looks totally different now!

Download Top 20 weighted by population

Switzerland

Austria

New Zealand

Uruguay

United States

Norway

Slovenia

Denmark

Finland

Canada

Australia

Singapore

Germany

Netherlands

Spain

Israel

France

Czech Republic

Greece

I was somewhat surprised to see Switzerland, Austria and New Zealand and Uruguay on top! Concerning Uruguay, I know that they use Sage at University.

Download Top 20 weighted by "internet users"

Niger

Uruguay

Guatemala

Austria

Greece

Israel

Switzerland

Puerto Rico

Ethiopia

Mali

Portugal

Czech Republic

New Zealand

Ireland

Australia

Spain

Armenia

France

Denmark

For me, that's also rather interesting. Of course, those countries with only a few internet users are easily on top (Niger), but e.g. Guatemala has more than 1 million users and so far I have never heard of them using Sage. In this context, our top 3 from the pure download numbers are way down below: USA #23, Germany #21, France #19!

Now the important questions:

What does that say about Sage adoption? Market potential? Is Uruguay a maths country and the USA not? Does it depend on the average income, GDP, ... (Switzerland & Austria vs. Uruguay & Guatemala?!?!) ... or just statistical noise?

If you want to see the whole data: online Webpage, CSV, ODS

Update:

Here the same weighted top-20 lists for "Visits" (a session of one or more pages impressions on sagemath.org or an related website (mirror, wiki, etc.))

Visists weighted by Population:

Iceland

Austria

Martinique

Switzerland

Luxembourg

New Zealand

Slovenia

Norway

Canada

Denmark

Australia

Finland

USA

Netherlands

Germany

Spain

Sweden

Uruguay

United Kingdom

France

Visits weighted by internet users:

Martinique

Iceland

Austria

Switzerland

Uruguay

Greece

Guatemala

Israel

Luxembourg

Australia

Germany

Portugal

Slovenia

Spain

Denmark

New Zealand

Ireland

Finland

Hungary

Norway

France

USA

Canada

Puerto Rico

United Kingdom

Update: whole spreadsheet, also for visits: online Webpage, CSV, ODS

ihhhehks fingers with tiny condoms

2009-07-31T16:23:00.003+02:00

Just when I wanted to do some vintage maths, I found this:

;-)

UPDATE:
They acually rescanned those pages, now the font is darker. Condomfingers are gone ;)

Sage Downloads - Spring 2009 Edition

2009-07-13T21:51:00.010+02:00

This post is about Sage download statistics. It is not really exact science, but good enough to measure tendencies. It uses JavaScript on all download pages of the mirror sites and tracks clicked download links by assigning them certain values. Therefore, it misses those situations where somebody downloads "directly", uses wget, has JavaScript disabled or scripts blocked. So, the actual numbers are higher. Said that, here are the numbers for April, March and June 2009:

Total Downlods:

Apr 5, 2009 - Apr 11, 2009	1110
Apr 12, 2009 - Apr 18, 2009	964
Apr 19, 2009 - Apr 25, 2009	1082
Apr 26, 2009 - May 2, 2009	1197
May 3, 2009 - May 9, 2009	1005
May 10, 2009 - May 16, 2009	1001
May 17, 2009 - May 23, 2009	1160
May 24, 2009 - May 30, 2009	1169
May 31, 2009 - Jun 6, 2009	1298
Jun 7, 2009 - Jun 13, 2009	1212
Jun 14, 2009 - Jun 20, 2009	970
Jun 21, 2009 - Jun 27, 2009	1079

There is no clear tendency, maybe a bit more at the end of the semester but falling since the end of it. Day-to-day stats are rather linear, too.

Distribution of Operating Systems:

microsoft_windows	5668	39%
linux/32bit	3109	22%
src	2101	15%
apple_osx/intel	1515	11%
linux/64bit	1290	9%
apple_osx/powerpc	364	3%
linux/atom	157	1%
apple_osx	85	1%
solaris	54	0%
src-old	10	0%
linux/itanium	4	0%

Linux/32bit:

sage-3.4-linux-Ubuntu_8.10-i686-Linux.tar.gz	559	17.98%
sage-3.4.1-linux-Ubuntu_8.10-sse2-i686-Linux.tar.gz	430	13.83%
sage-3.4.2-linux-Ubuntu_8.10-sse2-i686-Linux.tar.gz	415	13.35%
sage-4.0-linux-Ubuntu_9.04-sse2-i686-Linux.tar.gz	248	7.98%
sage-4.0.1-linux-Ubuntu_9.04-sse2-i686-Linux.tar.gz	215	6.92%
sage-3.4-Fedora_release_9-i686-Linux.tar.gz	171	5.50%
sage-4.0.2-linux-Ubuntu_9.04-i686-Linux.tar.gz	142	4.57%
sage-3.4-linux-PentiumM-ubuntu-8.04.1-i686-Linux.tar.gz	123	3.96%
sage-3.4-linux-Debian_GNU_Linux_5.0_lenny-i686-Linux.tar.gz	69	2.22%
sage-3.4.1-linux-Debian_GNU_Linux_5.0_lenny-sse2-i686-Linux.tar.gz	62	1.99%
sage-3.4.2-linux-Debian_GNU_Linux_5.0_lenny-sse2-i686-Linux.tar.gz	62	1.99%
sage-4.0.1-linux-Debian_GNU_Linux_5.0_lenny-sse2-i686-Linux.tar.gz	49	1.58%
sage-4.0-linux-Debian_GNU_Linux_5.0_lenny-sse2-i686-Linux.tar.gz	47	1.51%
sage-4.0.2-linux-Debian_GNU_Linux_5.0_lenny-i686-Linux.tar.gz	47	1.51%
sage-3.4.1-linux-openSUSE_11.1_i586-sse2-i686-Linux.tar.gz	44	1.42%
sage-3.4-linux-Mandriva_Linux_2009.0-i686-Linux.tar.gz	43	1.38%
sage-3.4-linux-openSUSE_11.1_i586-i686-Linux.tar.gz	42	1.35%
sage-3.4-linux-CentOS_release_5.2_Final-i686-Linux.tar.gz	34	1.09%
sage-4.0-linux-CentOS_release_5.2_Final-sse2-i686-Linux.tar.gz	31	1.00%
sage-3.4.2-linux-openSUSE_11.1_i586-sse2-i686-Linux.tar.gz	27	0.87%
sage-4.0-linux-openSUSE_11.1_i586-sse2-i686-Linux.tar.gz	24	0.77%
sage-4.0.1-linux-openSUSE_11.1_i586-sse2-i686-Linux.tar.gz	24	0.77%
sage-3.4-linux-Debian_GNU_Linux_4.0_etch-i686-Linux.tar.gz	22	0.71%
sage-4.0.1-linux-mandriva32bit_linux_2009-sse2-i686-Linux.tar.gz	22	0.71%
sage-3.4.1-linux-CentOS_release_5.2_Final-sse2-i686-Linux.tar.gz	21	0.68%

No surprises here, Ubuntu leads them all, then Fedora and Debian. Linux 64bit looks the same.

Country, Top 50

United States	5017	34.94%
Germany	1402	9.77%
France	693	4.83%
United Kingdom	668	4.65%
Italy	643	4.48%
Spain	487	3.39%
Canada	460	3.20%
China	413	2.88%
Japan	286	1.99%
Australia	255	1.78%
Brazil	254	1.77%
India	240	1.67%
Mexico	215	1.50%
Switzerland	192	1.34%
Netherlands	182	1.27%
Austria	168	1.17%
Portugal	135	0.94%
Belgium	134	0.93%
Greece	133	0.93%
Sweden	127	0.88%
Poland	119	0.83%
Russia	118	0.82%
Czech Republic	106	0.74%
Argentina	95	0.66%
South Korea	92	0.64%
Finland	89	0.62%
Israel	89	0.62%
New Zealand	83	0.58%
Norway	83	0.58%
Taiwan	81	0.56%
Denmark	73	0.51%
Colombia	72	0.50%
Hungary	58	0.40%
Singapore	56	0.39%
Romania	51	0.36%
Ireland	47	0.33%
Turkey	46	0.32%
Lithuania	45	0.31%
Peru	41	0.29%
Slovenia	41	0.29%
Thailand	41	0.29%
Indonesia	36	0.25%
Philippines	33	0.23%
Slovakia	32	0.22%
Croatia	31	0.22%
Panama	31	0.22%
Uruguay	31	0.22%
Chile	30	0.21%
Iceland	30	0.21%
Hong Kong	24	0.17%

It would be interesting to score them against some index, like, population, GDP and similar. And then fit the factors to understand, why Brazil is next to China for example ...

By the way, overall visits to the website during that timespan were rather constant. There were over 100,000 unique visitors, no changes since my last updates on the website concerning other parameters and Google is our main friend among all search engines. All major traffic sources:

google 55,654 31.47%

(direct) 39,037 22.07%

sagemath.org (another page there) 29,638 16.76%

en.wikipedia.org (referral) 3,643 2.06%

groups.google.com (referral) 2,928 1.66%

Download Website Redesign

2009-07-12T21:07:00.007+02:00

What is a great software like Sage worth without the ability to get your hands on? Nothing!

That's why it is important to provide a good download! Fast downloads a dependent on your location and that of the server. For example this means that a European Server works better in Europe (alghough that's not really true, some European servers also work very well in the US).

Until last week there was one heavily used dedicated download link and the possibility to alternatively choose a mirror. That has changed in a way where the dedicated primary download link is replaced by an overview of all mirrors. Now, everyone is "forced" to choose the download option that suits best! The second reason is, that the main server got slow since most oft the downloads happened from there and i.e. only few of the European users downloaded from the French mirror.

Additionally to the redesign, I contacted several server admins and extended the list of mirrors. Now, Europe is covered by serveral mirrors, also Russia, and what's still missing is South America and Central-South Asia. I'm still waiting for answers from server admins over there.

Now some numbers from the last two weeks, comparing Mondays to Fridays.

Jun 29th - Jul 3rd:

1. www.sagemath.org 53.48%

2. www.sagemath.fr 8.44%

3. sage.math.washington.edu 7.70%

4. modular.math.jmu.edu 7.57%

5. sagemath.org 4.84%

6. modular.fas.harvard.edu 3.88%

7. www.cecm.sfu.ca 2.33%

8. ftp.kaist.ac.kr 2.11%

9. echidna.maths.usyd.edu.au 2.02%

10. ftp.sh.cvut.cz 1.99%

As you can see, since *sagemath.org and sage.math are behind the same network, far more than half of the activity happend on the primary server. The week before it was even above 70%!

Now the numbers after the redesign:

Jul 6th - Jul 10th:

1. modular.fas.harvard.edu 17.69%

2. mirror.switch.ch 14.98%

3. www.sagemath.fr 14.22%

4. sage.math.washington.edu 11.74%

5. www.sagemath.org 9.32%

6. modular.math.jmu.edu 8.95%

7. ftp.riken.jp 4.65%

8. www.cecm.sfu.ca 4.07%

9. freethemes.mirror.aarnet.edu.au 3.50%

10. ftp.sh.cvut.cz 3.13%

Numbers massively differ after the redesign. Nearly only 20% of the activity on the main server is left, everything has moved to the other servers. Top server is located in Boston, but immediately followed by two servers in Europe: Switzerland and France. Also, the countries of the clients fit to the mirror locations. So, they actually choose and understand what to do ;) I'll probably post about the 4.1 release and the distribution around the world of Sage downloads in my next posting.

My next project is to find an easy way to detect if a server is updated or lags behind. Then, I want that this script updates the website automatically and thus the chances of hitting an outdated or broken server are very low. I hope that's not too difficult.

Happy downloading, Harald

Sage Mirrors Revamp

2009-07-05T11:21:00.004+02:00

Until now, on all download pages was a dedicated main download link for Sage. It pointed to the master server in Seattle. The problem is, that traffic increased and the server got slower. There was always the possibility to use a mirror, but it was only used rarely. More than 50% of all downloads still happened to be from the master server (sagemath.org + sage.math).

Now, the list of mirrors has moved into the download box area on all download pages. That should be a strong push for the use of mirrors. Also, non-US mirrors in bold should even work well outside Europe.

Numbers for last month, June 2009:

# | server | number of accesses | percentage

1. www.sagemath.org 13,467 47.89%

2. www.sagemath.fr 4,160 14.79%

3. sage.math.washington.edu 3,911 13.91%

4. sagemath.org 1,440 5.12%

5. modular.math.jmu.edu 1,396 4.96%

6. modular.fas.harvard.edu 1,047 3.72%

7. ftp.kaist.ac.kr 633 2.25%

8. www.cecm.sfu.ca 486 1.73%

9. modular.math.washington.edu 435 1.55%

10. echidna.maths.usyd.edu.au 339 1.21%

Also, notice the 15% for France. This will change, since Euopre is no longer covered by only one mirror.

Harald & Minh

two new mirrors

2009-06-26T12:13:00.006+02:00

Sage only had one foot in Europe for the last months. It was the very busy French mirror. Statistics showed that it was the most often accessed mirror of all and numbers were even increasing release by release. The upside is, there is growing interest in Sage in Europe - the downside a possible bottleneck in distributing Sage. I asked around and well, long story short: finally we have two new high quality mirrors in Europe:

Big thanks!

May the sageification of Europe continue - world domination soon to follow ;)

If you are also able to help distributing Sage, contact the webmaster.

omegle proxy conversation

2009-06-02T12:11:00.002+02:00

in case you are really bored:

sage + google wave

2009-05-30T18:04:00.001+02:00

google wave is a new type of web 2.0 hosted communication, presented at google's i/o conference a view days ago. http://wave.google.com . it is very early to tell what it really is, but it could be big. it is very open and also consists of an open protocol for communication, that can be used (basically) for everything - and that's where i started to think about sage. but first, i explain what i think it does and how sage could play a role in there!

a server (not necessarily google - it's more like jabber/xmpp where everybody could host a server and servers talk to each other if users use different servers) hosts the "communication", called "wave". that's a tree-like structure of data, replies, extensions, meta-info, etc. if someone modifies something or adds a reply, every other participant sees the modification in real-time.

there are also artificial participants, called robots. they can also do things just like a regular user. example: spellchecking! a spellchecker analyzes all text and if something is odd, it annotates/modifies the text.
okay, how works synchronization? basically, all operations happen on the server. i think it is an abelian group so that there are no "destructive" operations - only invertible - that cannot destroy the state-flow and the sum of all state changes is the current state. therefore, there is only one thread of communication for all participants. if something happens (lost connection), everything is re-synced fast.

the interesting point is, there are also gadgets: interactive elements for all participants (an example is a chess game) and that's where i think sage could be used. basically, my idea is to implement a button to create a cell from the notebook. then, you enter the url of a sage server + your credentials. now, input is sent to the server (also, autocomplete ....) and you get the answer back and a new cell is created. if i understand it correctly, the server is actually talking to sage, so it is possible that several users edit at the same time and the actual cell-data is saved inside this "wave".
what's missing is formatting the formulas - but there is also mathml which could do it.

i applied for an early developer sandbox access, once i know more about this i'll tell you more.

booom

2009-05-25T20:21:00.000+02:00

yet another blogstart!