According to
this test,
sympycore is from 2.5x to 5x faster than Maxima. This is an absolutely fantastic result and also a perfect certificate for Python in scientific computing. Considering that we compare pure Python to LISP.
Ok, this made us excited, so we dugg deeper and ran more benchmarks. But first, let me say a few general remarks. I want a fast CAS (Computer Algebra System) in Python. General CAS, that people use, that is useful, that is easily extensible (!), that is not missing anything, that is comparable to Mathematica and Maple -- and most importantly -- I want it now and I don't care about 30 years horizons (I won't be able to do any serious programming in 30 years anyway). All right. How to do that? Well, many people tried... And failed. The only opensource CAS system, that has any chance of becoming the opensource CAS, in my own opinion, is
Sage. You can read more about my impressions form Sage
here. I am actually only interested in mathematical physics, so basically Sage.calculus. Currently Sage uses Maxima, because Maxima is old, proven, working system and it's reasonably fast and quite reliable, but written in LISP. Some people like LISP. I don't and I find it extremely difficult to extend Maxima. Also even though Maxima is in LISP, it uses it's own language for interacting with the user (well, that's not the way). I like python, so I want to use Python. Sage has written Python wrappers to Maxima, so Sage can do almost everything that Maxima can, plus many other things. Now. But the Sage.calculus has issues.
First, I don't know how to extend the wrappers with some new things, see my
post in the sage-devel for details, it's almost 2 months old with no reaction, which shows that it's a difficult issue (or nonsense:)).
And second, it's slow. For some examples that Sage users have found out, even
SymPy, as it is now, is 7x
faster than Sage and sympycore 23x faster and with the recent speed improvements 40x faster than Sage.
So let's improve Sage.calculus. How? Well, no one knows for sure, but
I believe in my original idea of pure Python CAS (SymPy), possibly with some parts rewritten in C. Fortunately, quite a lot of us believe that this is the way.
What is this sympycore thing? In sympy, we wanted to have something now, instead of tomorrow, so we were adding a lot of features, not looking too much on speed. But then Pearu Peterson came and said, guys, we need speed too. So he rewrote the core (resulting in 10x to 100x speedup) and we moved to the new core. But first, the speed isn't sufficient, and second it destabilized SymPy a lot (there are still some problems with caching and assumptions half a year later). So with the next package of speed improvements, we decided to either port them to the current sympy, or wait until the new core stabilizes enough. So the new new core is called sympycore now, currently it only has the very basic arithmetics (and derivatives and simple integrals), but it's very fast. It's mainly done by Pearu. But for example the latest speed improvement using sexpressions was invented by Fredrik Johansson, another SymPy developer and the author of
mpmath.
OK, let's go back to the benchmarks. First thing we realized is that Pearu was using CLISP 2.41 (2006-10-13) and compiled Maxima by hand in the above timings, but when I tried Maxima in Debian (which is compiled with GNU Common Lisp (GCL) GCL 2.6.8), I got different results, Maxima did beat sympycore.
SymPyCore:
In [5]: %time e=((x+y+z)**100).expand()
CPU times: user 0.57 s, sys: 0.00 s, total: 0.57 s
Wall time: 0.57
In [6]: %time e=((x+y+z)**20 * (y+x)**19).expand()
CPU times: user 0.25 s, sys: 0.00 s, total: 0.25 s
Wall time: 0.25
Maxima:
(%i7) t0:elapsed_real_time ()$ expand ((x+y+z)^100)$ elapsed_real_time ()-t0;
(%o9) 0.41
(%i16) t0:elapsed_real_time ()$ expand ((x + y+z)^20*(x+z)^19)$ elapsed_real_time ()-t0;
(%o18) 0.080000000000005
So when expanding, Maxima is comparable to sympycore (0.41 vs 0.57), but for general arithmetics, Maxima is 3.5x faster. We also compared GiNaC (resp. swiginac):
>>> %time e=((x+y+z)**20 * (y+x)**19).expand()
CPU times: user 0.03 s, sys: 0.00 s, total: 0.03 s
Wall time: 0.03
Then we compared just the (x+y+z)**200:
sympycore:
>>> %time e=((x+y+z)**200).expand()
CPU times: user 1.80 s, sys: 0.06 s, total: 1.86 s
Wall time: 1.92
swiginac:
>>> %time e=((x+y+z)**200).expand()
CPU times: user 0.52 s, sys: 0.02 s, total: 0.53 s
maxima:
(%i41) t0:elapsed_real_time ()$ expand ((x + y+z)^200)$ elapsed_real_time ()-t0;
(%o43) 2.220000000000027
Where GiNaC still wins, but sympycore beats Maxima, but the timings really depend on the algorithm used, sympycore uses Millers algorithm which is the most efficient.
So then we tried a fair comparison: compare expanding x * y where x and y are expanded powers (to make more terms):
sympycore:
>>> from sympy import *
>>> x,y,z=map(Symbol,'xyz')
>>> xx=((x+y+z)**20).expand()
>>> yy=((x+y+z)**21).expand()
>>> %time e=(xx*yy).expand()
CPU times: user 2.21 s, sys: 0.10 s, total: 2.32 s
Wall time: 2.31
swiginac:
>>> xx=((x+y+z)**20).expand()
>>> yy=((x+y+z)**21).expand()
>>> %time e=(xx*yy).expand()
CPU times: user 0.30 s, sys: 0.00 s, total: 0.30 s
Wall time: 0.30
maxima:
(%i44) xx:expand((x+y+z)^20)$
(%i45) yy:expand((x+y+z)^21)$
(%i46) t0:elapsed_real_time ()$ expand (xx*yy)$ elapsed_real_time ()-t0;
(%o48) 0.57999999999993
So, sympycore is 7x slower than swiginac and 3x slower than maxima. We are still using pure Python, so that's very promising.
When using sexpr functions directly then 3*(a*x+..) is 4-5x faster than Maxima in Debian/Ubuntu. So, the headline of this post is justified. :)
ConclusionLet's build the car. Sage has the most features and it is the most complete car. It has issues, some wheels need to be improved (Sage.calculus). Let's change them then. Maybe SymPy could be the new wheel, maybe not, we'll see. SymPy is quite a reasonable car for calculus (it has plotting, it has exports to latex, nice, simple but powerfull command line with ipython and all those bells and whistles and it can also be used as a regular python library). But it also has issues, one wheel should be improved. That's the sympycore project.
All those smaller and smaller wheels show, that this is indeed the way to go, but very important thing is to put them back in the car. I.e. sympycore back to sympy and sympy back to Sage and integrate them well. While also leaving them as separate modules, so that users, that only need one particular wheel, can use them.
Here is something I wrote some while ago, hope this will be useful for some World of Warcraft p(l)ayers. Has no other relation to Linux or Debian, except it works on it flawlessly. Also note that 2.3.2 patch went live last week.
It is not a secret anymore that mages of all talent specs will be getting a present when patch 2.3.2 hits the live realms - the Ice Block will be available from any friendly mage trainer for a nominal fee. Currently this spell requires a whopping 21 point investment into the Frost talent tree. With patch 2.3.2 Ice Block will become trainable to all mages, Ice Barrier will take it’s place in the talent tree and a new awesome talent - Icy Veins will take the place of the Ice Barrier, so that even frost mages have a new toy to gain in this 2.3.2 mage winterly fiesta.
While there is a significant proportion of mages that are frost for PVP or grinding survival purposes, a large proportion of mage population have never used Ice Block or haven’t used it for a while. For that reason, the rest of this article (after the break) will explore all the great uses of Ice Block, that all of you can look forward when patch 2.3.2 hits the live realms (or sooner, if this article convinces you to re-spec frost :)).
So, what does the Ice Block do? When you cast the Ice Block, it purges you from all debuffs and releases you from all snares, you get frozen solid into a large block of ice (same look as hunter’s ice trap) and for 10 seconds you are immune to all damage, but unable to do anything - no moving, casting anything, no bandages, nothing.
Getting rid of: Ice Block is a buff, so you can get out of the Ice Block by right-clicking it off at any time. Another way for keyboard-addicted mages is to press Ice Block keybinding button again (after the global cooldown is done). Enemy shamans can purge it off you and priests can mass dispel your Ice Block in PVP.
Cooldown: the Ice Block is on 5 minute cooldown, which can be ended early using the Cold Snap talent from the mage frost tree. To prevent mages casting two ice blocks back to back by using the Cold Snap, Blizzard added the Hypothermia debuff (in 2.1) that prevents you from casting the Ice Block 30 seconds after the last cast.
The main use of Ice Block is to survive pulling aggro in groups. While we all know that “good mages don’t draw aggro”, experienced players can easily show situations when drawing aggro is not mages fault and surviving that can be the difference between a wipe and a win. When Ice Block is used, your threat is NOT reduced, so you need to stay inside the Ice Block at least until you are under 130% of the tanks threat. After you Ice Block, the mob will run to the next person on the threat list. If your tank is dead, Ice Block will send the mob to another DPS or healer giving you a couple seconds to nuke it when it will be running back to you again. I have seen a few bosses loose their last 2-3% of health running between mages with Ice Block and hunters with Feign Death after a unfortunate death of the main tank.
Ice Block is a great way to get rid of almost all debuffs that exist in the game: warlock DoTs, stuns, snares, polymorph, mind control … Even boss debuffs go away in a snap - Garrote from Moroes, Demonic Chains from Illhoof and many more deadly debuffs are no threat to a mage with an Ice Block ready.
Ice Block can be used as an alternative to Slow Fall if you’re out of Light Feathers. Just do not cast it too high in the air - if the 10 seconds tick by and you haven’t hit the land yet .. you could as well kiss 10% of your durability goodbye.
When solo grinding there is noone to draw aggro from you, so the mobs will continue to beat on your personal icy sculpture, however during that time your Water Elemental or other battle pets could be dishing some damage, your cooldowns will tick down and also you will also regenerate some mana inside the Ice Block. The Ice Block could thus make the difference between your death and Frost Nova+Blink+Blizzard and their death.
Have you had some fun experience with Ice Block? Leave a comment so that others could repeat it too!
(Disclaimer: I work for 
Last weekend was as hectic as my life has been lately: I have been trying to restore sanity into my NSLU2, I went to a lecture from 
Every time I read a blog post about a blog having moved or a
redesign , I swear to myself, again and again, that I would never
do alike.
And yet, having just finished the migration of all my posts from
There have been several long-term wishlist bugs on Mutt to include the
(in?)famous "sidebar" patch. It adds a panel on the left side of the screen to
list mailboxes with message counts.
We do ship several patches with Debian's Mutt package that are not considered
for inclusion by the upstream authors, but this one is different. It touches
the core of the UI renderer and adds extensive counting of messages. There's
been quite a hype about the patch, it was even included in the (now
discontinued [1]) mutt-ng fork. Unfortunately, the patch was technically questionable, it
was written for the Mutt tarballs and didn't easily apply to CVS, and most
versions floating around contained lots of cruft like backup files and
temporary editor files. Furthermore, it is far from bug-free and even segfaults
occasionally.
Some months ago we decided we would build a second binary package to put the
patch in so we don't destabilize the standard package. Thanks Dann Frazier, we
got a clean patch, Adeodato had the right idea on how to build two binaries
from the same, differently-patched source (make install would run havoc, the
trick was to build the patched version before the regular one), and I
resolved some more involved conflicts with the maildir-mtime patch.
So, finally, there it is:
I just called the ICU for an update before I head in for the day. She's
apparently doing well, and can probably transfer out of the ICU later today,
although apparently beds are tight in the ward.
Update 1
I've managed to find somewhere with EVDO access, so I can update this in
between ICU visits.
She's looking really good this morning. She asked for some 7up, because her
throat's really dry and sore from being intubated. She had something to eat
at 6am. She hasn't had much sleep though, because the ICU has been too busy.
She's getting turned every two hours, which isn't terribly enjoyable, but
her pain is manageable. She's such a trooper.
Update 2
Sarah's continuing to do well. The nurse sat her up on the side of her bed
for lunch, and had half a roast beef sandwich and some fruit. Her throat's
still pretty sore, and she's really preferring the liquids. Apparently her
blood sugar is a bit high (something that can happen post-operatively) so
they gave her some insulin before lunch.
Getting her back down again looked a bit painful, as did shuffling her up
the bed.
Apparently there's a bed with her name on it in the intermediate ICU, so as
soon as the doctor's order comes through to move her, she'll be moved.
They'll also take out the central line and one of the peripheral lines at
that time.
Update 3
Last update today. Sarah was moved out of the ICU and into intermediate
intensive care (where she'll remain until she's discharged) at 2:25pm. She
got a private room again, which is very fortunate. It's nice and quiet, so
she should get a good night's sleep. I can stay the night as well.
One of the doctors from the team looking after her came by at about 5:50pm.
She said the chest drain can come out in the next day or two. They took
another x-ray this afternoon to check on some pleural effusion that they
were worried about. When we asked the doctor about it this evening, she
described it more as trapped air than trapped fluid, and that it should work
itself out in the next few days. The x-ray showed that it was "stable", in
that it hadn't really changed from the x-ray in the morning. They'll take
another x-ray tomorrow morning to see how it's going.
Other than that, she's continuing to do really well. The pain seems
manageable. She got up into a chair for dinner (with help). They didn't give
her any more insulin beforehand, so I presume her blood sugar is settling
down again.
Assume for a moment that you have 148 hosts logging, via syslog-ng, to a central host. That host is recording all log entries into an MySQL database. Assume that each of these machines is producing a total of 4698816 lines per day.
(Crazy random numbers pulled from thin air; globviously).
Now the question: How do you process, read, or pay attention to those logs?
Here is what we've done so far:
I am very saddened by the state of the IT industry. It seems like nearly
everyone who works in or around IT is, to put it bluntly, a cowboy. There
appears to be very little desire for actually helping people;
instead all I see is a very large number of people circling around looking
for the next person they can make a quick buck off. In short, most of the
IT industry is composed of people who are little better than shysters and
conmen.
As a case in point, I recently had contact with someone who is trying to
get an online store running. They've been trying, unsuccessfully so far,
for several months. They've been screwed over by basically every
IT-related person they've had contact with so far. Now, after all of
their suffering, they've finally gotten in contact with me. Most of their
money is gone, and they're deeply behind schedule. So I'm left trying to
pull a miracle job in little time and with little money. Yes, I could
shoo them away, because they're asking for more than they can afford, but
there's a little spark of helpfulness left in me, and I'll try to get them
going as best they can with what they've got.
If they'd found someone competent right at the beginning, they'd have been
fine. They started with sufficient cash and time to produce a good end
result. But chancing upon someone decent doesn't have good odds in IT;
it's a bit like winning the lottery.
This story isn't unique in my personal experience, by any stretch. There
seems to be a near-endless procession of non-technical people who come out
of their encounters with the IT industry battered and bruised, whether it
be on the web, in their business infrastructure, or their personal
computing needs.
While it's easy to blame the customer for not managing themselves and
their computing properly, I don't think it's fair to lay the blame on them
-- to me, that's like blaming the patient for dying on the operating
table, when the responsibility must lie, prima facie, with the surgeon.
It's the surgeon, after all, who is the (presumably) trained and
experienced professional in the relationship, and it is his
responsibility, primarily, to ensure that everything goes smoothly[
Yesterday after dinner we spontaneously ended up having a
I spent two hours answering the phone, ribbing the clients affectionately
before sending their calls off to different areas in the firm. It was like I
couldn't get enough. I had to stop when Carol came back to her desk and
demanded to know what the hell I was doing.
I rejected the first fourteen answers that came to mind, and instead
gave her a shrug, a wink, and a fingersnap. Then like a Carmelob, I
scuttled away and strolled back across town to my office.
My dyspeptic boss tapped his foot in a hostile manner. He demanded to
know where I had been. I rejected the first three answers that came
to mind, and simply responded that I had been answering phones.
Also I quit. It seemed the thing to do.
Explaining to my colleagues that I had just freed up a bit of time,
I returned to Carol's office, where I found her rocking back and
forth in the corner.
I turned off her light. It seemed the thing to do.
I've been taking a little bit of time away from Debian and X to see what sort of fun stuff is out there that I've been putting off learning. Aside from finding what looks to be a good fitness training plan for the next year (and hopefully beyond), I've been looking at different programming languages. One that I found most recently is 
After my many 
