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Showing posts from 2007

Fixing an iPod mini

Many times the answer is on the 'net, so when I wondered if my dead iPod could be fixed I started Googling. This post is one of the answers I have found. To make a long story short: iPods do not like to fall on the floor, they use to stop working as a revenge on the careless user. iPod mini has an Hitachi microdrive (same size as a Compact Flash memory but thicker) inside.

You may wonder, as I did, if you can substitute the damaged microdrive with a solid state flash memory. The answer is yes. Have a look.



And yes, you can replace the 4GB microdrive with a 8, 16 or even 32GB Compact Flash card to boost your iPod capacity. You can also replace the battery if it is not holding a charge too. Just be aware that not all the CF cards work.

Between the devil and the deep blue sea

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When my son asked for a new MP3 with video player to replace his ancient Creative Zen micro I thought a new 8GB Creative ZEN will be a nice replacement. However the Zen micro units and the Zen V Plus have not been very reliable (at least not mine). It seems the obvious choice would be to go iPod nano. An option I would agree with but because my iPod decided not to allow writing new songs anymore a few weeks ago.

Several things seemed to favor the 8GB Creative ZEN: screen size almost double that of Ipod, a built-in radio and a built-in microphone enabling the use of the unit as a voice recorder. On the cons it was the size and thickness factors that played against Creative's.

Unfortunately, the 8GB unit was not easy to find, but somehow Santa managed to get one just in time. It was a disappointment to discover the unit display did not to work just after opening the box. However, just to follow the instructions we fully charged the unit and transfered a whole bunch of songs (data tran…

Still more problems with Ubuntu 7.10

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While I have to admit I am quite happy with the last Ubuntu version I have to mention several bumps I ran into:
To my surprise, the usual way of installing ssh server did not work as expected. After doing sudo apt-get install ssh I've got installed and running the ssh daemon, but no connection was possible. Well, not sure what happened, but now it works ... I cannot trace what exactly the problem was though it seems two daemon processes were launched by error.
Realplayer is another problematic application that use to work in previous versions but now it creates trouble.
The adobe Flash player is (almost a requirement if you want YouTube videos to play) another tool creating trouble at the moment. The install will fail but some magic can be done to get it working too.VMware's vmplayer is another example of this apparent regression of tools. It was working before but stopped working not. Fortunately help was on its way and it can be fixed too.None of these problems has been a show…

Gutsy ... we have a few problems

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The second system I installed Gutsy was probably angry with me. Or maybe I was just downplaying Murphy's laws. It was an old Asus Pundit-R computer and it was a mess.

The initial install went ok as I kept my /home partition untouched not to loose any data. However since the first moment the screen colors looked awfully washed out. Of course this same computer was just happy with almost any previous version of several flavors of GNU/Linux, so it had to be something new. While Google comes in handy most of the time, the problem is to choose the right keywords. It took me a while (more than I am willing to admit) to find this bug report and the solution.

And while doing the silly thing with the Ubuntu logo above, I discovered the GIMP version that comes with Gutsy fails to open a URL. A feature that has been working for ages. (Fix:sudo apt-get install gimp-libcurl).

In the process of fixing the graphics driver problem something happened to compiz that now prevents me to use any graphica…

Testing Ubuntu 7.10

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After some weeks waiting to allow the news to settle, I've decided to install the new release of Ubuntu known as Gutsy Gibbon. I have started with my laptop that was most needed of an upgrade as it was still running the same version I installed 18 months ago. At the time, Ubuntu required me to tweak several things to get the laptop running fine and still the memory card reader was a no go.

This time installation was faster and everything worked first time (all but the WLAN led, while WLAN worked ok the led showing it was on didn't). No need to fight with any xorg config file to get the right screen resolution. Suspension worked nicely too (but I needed to go to the preferences menu to select the power save operations I wished: closing the lid will suspend the system). For the first time Firefox prompt a Java runtime install that worked ok, giving you the choice of what virtual machine you wanted, too.

I've read some claims that battery consumption might be higher on this ne…

G-NOTE electronic notepad software

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Given the number of downloads, and the fact I wanted to use the red pen myself, I patched my previous converter code to include that.

As before, the perl source code is available for download. The program will convert a g-note proprietary file format into an SVG file that at least Inkscape software (the one I use) is happy with.

Luckyly one reader provided this link with the file format specs.

Just type dnt2svg.pl your_dnote_file > converted.svg

Windows users need to know they can get a free perl interpreter from ActiveState. Those with Apple OS X already have it in place (but you still need to know of to use a terminal).

The French kiss

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New rules in France have been set up to punish on-line exchange of files. The new deal between the French administration, the recording industries and the Internet service providers is supposed to protect the artists' revenue.

The deal is supposed to be against on-line movie and music exchange but I am not sure how easy may be to detect that a given user is downloading a song whose rights belong to a French corporation or artist. So it may well be easier to rule out any file exchange, just in case. We will see...

Not everybody agrees on the idea that preventing music or video sharing over the Internet is going to improve sales figures, though. If the system they are putting in place in France does work, it may well be a market to watch carefully. I won't be surprised if, instead of the expected results (higher revenue for artists), a significant decrease on Internet users happens. Because of this, I think this is a social experiment we need to pay close attention to.

Do not forge…

VectorMagic: on-line vectorisation

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Many vector drawing programs do include a vectorisation tool so a vector representation of a bitmap can be obtained. I have used many times the one that comes with Inkscape program.

However, I've just learned of another tool you can use. The fact the tool comes from Stanford makes you hope for very good or superb results.

The picture on the left is a bitmap of a vectorised bitmap. The usefulness of that is just as a sample (but, of course, you do not want to get a bitmap of your vectorised output). The picture was taken from a recent Google Talk at our university.

What makes this new tool unique is the fact it is an online service. You upload the bitmap from your web browser and after a few selections you download the result in either EPS, SVG or PNG format (the latter is a bitmap format though).

The comparison you can find on the tool site shows an impressive performance compared to other vectorisation tools on commercial software (from Adobe and Corel).

Update: Since this entry was w…

GIMP and Leopard can now work together

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I reported some days ago I could no longer use The GIMP on the newest OS X 10.5 , aka Leopard. It transpired the problem was due to changes on X11 support. Apple has moved from Xfree86 to X.org implementation and this move created some trouble for several Xwindow applications.

Fortunately the fixes are already available and a new binary I found here is working like a charm on our iMac (this subtle change on iMac's ownership claim has not been yet noticed by my wife).

BTW, if you want to try the Time Machine in Leopard you need to now that the external hard disk you use needs an HFS+ partition. So if you just have another one the drive will need to be repartitioned and you will lose all your data. Warning messages are given before though.

If you used arhive install, as I did, you'll have around 12 GB with a copy of your old Tiger setup. It may be a good idea to delete it (provided you already had another backup) before using the Time Machine for the first time.

Drop down lists for country selection

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I am sure you've used many times a drop down list to chose from a set of limited choices. One common use is to mark the country when specifying a shipping address.

Some websites default to your own country, which is a good thing for the locals but eventually other people will have to select another value from the list.

As I am currently based in Spain everything I buy from other countries does not default to my country so I am forced to go down the list. There is a shortcut that works on different operating systems which is pressing the first character of the word you are looking for to go to the first, second, third element, and so on of names starting with that same character. Sometimes this can be much faster than using the mouse.

However, I have discovered that the common way of storing this lists does not make my life very easy when searching for my own country. There are several problems:
Not all the site use the same list so you never know what is the location of the item you a…

Leopard upgrade blues

My wife's iMac is dead after the Leopard upgrade (I was about to tell you how fast was the delivery of the DVD from Apple's store). I've seen I'm not alone and I'm going to have to do another type of install that essentially will wipe out all the apps and config already done.

This is the feedback I left on Apple's feedback page:

I had an almost "virgin" one-month old aluminium iMac 20". I requested the upgrade DVD to go from Tiger to Leopard.

Now my system refuses to accept my password anymore. After a blue screen it gets back to asking me my password again (I'm positive I'm typing the right password). Now I have discovered many users are having the same problem.

Shame on you Apple. It's really not acceptable. None of the "rm" tricks proposed did fix the problem so I guess I'll have to go through the archive install. This ruined my day. I am not happy.

So be warned, do not expect the normal upgrade to work and reserve a ful…

Removing DRM from WMV files

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Did you ever wanted to play a file on a different device but you were prevented to do so because the file you bought had some nasty DRM inside?

Well, I did and I wanted to do something about it. There is a tool that seems to work nicely for this purpose and it does not involves cracking the DRM system. It is tunebite software. It somehow reminds me the idea of Total Recorder but now it does work with videos too.

The idea is quite simple: If you can play it you can record on-the-fly from your own computer. I guess it is easier to say than to do it. But this company seems to have done a pretty good job.

They claim doing this is not illegal but I cannot provide you legal advice. For me it did the work of enabling my wife watching a DRM-ed video on her Creative Vision:M, which by the way it is a better video "iPod" than Apple's.

Merging Arduino and Xbee

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There are many open source projects out there. Many of you are familiar with the concept of open source software, where the source code is made available. Not so common is the idea of open-source hardware. What is the idea here? You get the full details of the hardware and firmware as if it were just the code of an open source software project. It is about extending the openness of a project to the hardware and firmware levels.

Arduino is one of these open-source hardware projects. It is a family of small printed circuit boards powered by Atmel micro-controllers that can be programed. You develop the code for these micro-controllers using an Integrated Development Environment (IDE) also provided on the project's web-page, available for Windows, Linux or OSX. The IDE is based on Processing IDE I covered a while ago and the programming language is based on Wiring language. The goal is to make user life easier as the development is aimed to artists more than to engineers.

The micro-con…

Photo slideshows

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Digital photography brings yet another way to annoy friends and relatives. Digital photogtraphy is convenient, and you do not have to buy or develop film, so you may end up, like me, taking (and keeping) many shots that are not that great.

Thousands of pictures pile up on your hard drive but they are not in a format you can easily share with your grandma (unless she is Internet proficient). Two online services I have found quite useful are flickr and Google's Picasa. They make easy for you to share your photos even when you are on the go.

However, if you want to create something oriented for people who at most are capable of playing a DVD then you need other tools. Some DVD burning programs can help you creating a simple slideshow of your photos. However my experience is that just a sequence of pictures without a soundtrack is not something people are going to enjoy.

Another problem is that even if you have sound, the pictures without any motion look boring and uninteresting most of …

Kensington Expert Mouse

Contrary to what the name may suggest this device is not a mouse but a trackball. At around $100 it is an expensive alternative to traditional mice. Kensington trackballs have been around for more than 15 years and I have read good things about them.

I decided to judge by myself and I bought one unit. The bottom line is that except the annoying noise and feel of the scroll ring the device is quite nice. The optical tracking is hopefully more precise and less sensitive to dirt than older mechanical systems.

I have contacted Kensington customer support to report the problem, but given what I have read on the net it seems to be a common complaint from users. I have not yet heard from Kensington but I have thought you may want to "hear" and feel it by yourself before buying one unit.


Joost 1.0 beta is now available

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I've tried both versions, windows and osx, and they seem to work ok. The new era of P2P TV is here for you to decide whether it will stay or not. Joost image and sound quality are quite ok. Service is now open to everybody, you may want to give it a try.

Good-bye Mailinator?

I tried to use Mailinator.com service today unsuccessfully. It seems the popular passwordless free webmail service is not available now (being passwordless means that you should not use it for any private messages as anybody might have access to your messages if they figure out your mailbox name).

For several years, Mailinator was a useful allied for those not willing to give up their real email address when registering for a service or download.

They seem to have a blog. And nothing about shutting down the system is ever mentioned. So hopefully is just a technical problem they are experiencing as the domain name is paid for till 2011 by Mailinator's creator Paul Tyma. Pinging the server works, but the system rejects any http connection attempt.

Anyway, fear not as there are different interesting alternatives.

Update: They are back on-line!!

Another new iMac

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I have been fascinated with the idea of a silent computer and the new Apple iMac captured my attention when they created the new aluminum line.

Last time I bought a computer from Apple it ended up being used mostly by my wife. For this problem not to happen again I've just bought her a new iMac!. I am allowed to use it from time to time (mostly to install new software).

After a few hours of using the system I am more than happy with the looks, the clutter-free desktop and the silent operation (I guess that after several minutes of heavy load you will start listening some noise but this just has not happened yet). I've read it has three fans inside.

The main complain is that the unit is not user serviceable (say goodbye to upgrade your hard disk). However everything I've tried just worked out of the box, no problem at all. I only needed to look the documentation to learn how to suspend the system (press play 3 seconds on the remote or the power button or select suspend in the …

Google's new offspring

I've used for some time their Google Docs service that offered on-line Spreadsheets and Text editing and now the third complement has come to life: Presentations have been added to the mix and offer, like the other tools, easy collaboration among a group of users of the same documents.

I've used a shared spreadsheet for marking lab sessions across a group of teachers and it proved quite useful.

Of course none of these tools compare very well against a locally installed Office application, but it just uses on any networked computer and its free and your documents are accessible from anywhere on the net.

When you factor in the possible collaboration between several people on the same documents Google's proposal becomes much more attactive plus you save lots of emails.

Excel 2007 bug

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I've just read on Slashdot about an error in Excel's multiplication. Details can be found in this Google group thread. In short, it seems a multiplication whose result gives 65,535 (which is 2^16 -1 or 0xFFFF in hex) will return 100,000.

I haven't tested it myself yet, but it seems several other people did. I would be worried if I were using that software for any calculation.

Update: I've already tested and it happened indeed (see the picture). Cell A1 shows the offending formula and A2 shows you the result of that formula (which should be 65,535 instead). However, I've tested other multiplications whose result should be the same and they all seemed to work ok. That's funny. (BTW, decimal point is "," in my locale in case you are wondering).

HDR with RAW files

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While I mentioned HDR on a previous entry, at the time I comented the need of three (or more) different exposures to obtain an HDR image. More recently I have learned that you can use the same software to obtain the same result with just one photo.

The basic idea is that camera sensor have significantly more resolution than the 8 bits per color of JPEG. Some cameras -- unfortunately the most expensive ones -- allow you to access to the original sampled data. The so called RAW format. After some processing a JPEG file can be obtained changing, for example, the exposure one f-stop up or down (this is like dark-room magic).

In the above image I took a single exposure and I used Canon's RAW processing software to obtain three JPEG files with exposure values -1, 0 and +1 from the original shot. Then the three were combined with (the trial version of) Photomatix software.

Original shot is shown below for you to compare.











Update: Actually, thanks to one of your postings I've learned that …

Supress belief

After returning from holidays I've came across two different stories that somehow did not look right and turned out to be a scam or a hoax.

First one was a person who told me about a recent e-mail she got from a friend who, interestingly, claimed to be in Nigeria and lost her wallet in a cab. The twist was that the message was apparently coming from a real person that she knew.

I tend to be quite suspicious whenever somebody asks me money by email, specially if the requester is based in Nigeria (419 scam is a classic).

This time it was a new variation, based on hijacking a person's email account (gmail, hotmail, etc) so they take control of that person's email and they use his/her address book contacts. This way the person receiving the scam email believe they are talking to a person they know. If they are lucky you will rush to Western Union to wire the money trying to help your friend.

The second weird news came from a good friend who was worried about the news that spread …

Go home with the CD-ROM

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While on vacation in Sweden I started having a lot of pain on my lower back. I thought it might be a kidney problem and after a few days without the problem going away by itself I went to the Emergency Room at Sundsvall's hospital (sjukhus in Swedish in case you are wondering). Though I was kindly asked to return on the evening as my condition was not life threatening.

When I returned my condition worsen quite a bit and I was told to stay overnight at the hospital (not a good thing when you are on a vacation trip). Fortunately, after three days my blood tests had improved and I was allowed to leave the hospital. We were very lucky as our friends in Sundsvall helped us to go through this (once again, thank you very much guys!!).

While at the hospital they performed a CT scan to determine what and where the problem was. They found a 2.5mm stone leaving my right kidney and I was told the problem will likely dissappear without surgery, which luckily did.

When I left the hospital I was p…

Cups printing problem solved!

Some weeks ago I mentioned Ubuntu's Feisty was having a weird printing problem that I and many other people reported. It was unclear what was the triggering action and where the fault might be. And it seems it was for a a reason: While everybody thought the problem was in cups code, in the end it turned out the error was on another package.

D-Bus is a library that offers a high-level interprocess communication. This library might be used by cups if available. There was a bug on the last version on the library (used by both Debian and Ubuntu) that eventually caused pipes not to be closed properly. The net result was that the cups process was gathering more and more file descriptors till a limit was reached.

Thanks to the joint work of many users, Martin Pitt provided a fix for Ubuntu.

Your printing blues is over.

Wifi friends

I've got a call from a friend who was desperately trying to get Wi-fi working at home. The brand new PlayStation 3 was not able to use the home network as the broadband router was not configured as a DHCP server. The WiFi access point they had did not show up on any menu.

When I get there I realized the WiFi access point was either dead or the power supply was not fully operational, so the whole thing was actually dead. As I was trying to be of some help and because my friend did have two wireless cards I suggested he could use the so called ad-hoc mode to network wirelessly his two computers while the Playstation was connected using and Ethernet cable to the broadband router.

To get this working you need to connect one of the computers to an Ethernet port of the broadband router and then you share this connection so a second computer can use it too while it connects wirelessly to the first computer (no access point is involved here, so that is what this mode is called ad-hoc mode).…

A painful lesson

I bought some cheap airline tickets over the weekend for a family trip. I was asked to provide not only the names of the passengers but also their ID number,gender,title and birth-date. Quite annoying but I guess that might be of some use.

This morning I've got the tickets delivered from the online company and my son discovers there is an error in his lastname. I email the the seller to ask for a fix as, though there is yet enough time left, I do not want to procastinate about this.

My email gets answered quite fast but the directions given are somehow confusing: I should cancel the ticket and I should buy a new one. This approach in itself has two problems: On one hand being the tickets non-refundable cancelling means losing all the money (so I do no see any advantage for cancelling such a ticket) and paying, again, for the same ticket just to get your lastname fixed. But secondly, there is a chance of not getting the same schedule on sale in this second attempt of buying the ticke…

Hard drive upgrade season

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After having passed all the subjects one of my kids was asking for a hard disk upgrade. He wanted to double his 120GB harddisk. I have written before about tools you can use to get this job done, but I am not wise enough to follow my own advice, so I decided to try new approaches to the problem. I will tell you first what did not work:

I started partitioning the drive using fdisk and formatting the new partition using FAT32. My kid's data was stored on an NTFS partition but I thought FAT32 will be ok. Well ... it wasn't: While I could copy all the data the system refused to boot. Rescue disk and FIXBOOT or FIXMBR did not fix the problem, so I ended up thinking XP is not happy booting a large (240GB) FAT32 partition, so I did a conversion to NTFS using CONVERT.EXE having the new drive as a slave one. Conversion was successful but the booting problem was not going away.

Installing Ubuntu and GRUB in a small partition did not help me getting WinXP to boot, though Ubuntu did boot wi…

AMPL: A Modeling Language for Mathematical Programming

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In my quest to get some calculations done, as it seems my math knowledge is less than good enough, I have had to resort to use other tools I can handle. Serendipity led me to AMPL language developed at Bell Labs (by Brian W. Kernighan et al.).

AMPL is used by Operations Research practitioners to solve Linear Programming problems. But the fact that AMPL is mostly a language to express math problems does not mean it can solve them. If you have a LP problem you can express it using AMPL but you need a solver to actually solve the problem. AMPL can work with may different solvers (some free others are commercial) and the solver you use may also depend on the nature of your problem. For example, your LP problem might have non-linear constraints that some solvers can't deal with.

You can download a free student version of AMPL. You can also obtain different solvers and I am using the free student version of LOQO solver by Princeton's Robert Vanderbei. Another possible choice, without …

Meet Processing

The sample below shows a five minutes piece of code that animates a chain made of nine particles linked with springs. Although the inner core of Processing is made in Java, it is a nice tool for people not familiar nor interested on the full glory of details of Java applets but willing to create some graphical software.

Click on the applet to shake the chain ...





To view this content, you need to install Java from java.com


Built with Processing

Joost about to leave beta

I was told about Joost some time ago at the most unexpected place by a person I just met. After having lunch with Alvy (from Microsiervos), Francisco (Mystrands' founder) and Victor Fuente. Victor showed me Joost player on his laptop. It was kind of weird because we were having a drink by the beach and it seems that pub did have an open wifi with a decent bandwidth. I was shocked: that thing really worked quite decently, so I guess the result has to be even better on a standard Internet connection.

You still will need an invite while they are in beta to try it out, but you can register your email address to be paged once the beta is over.

But, what the heck it is that Joost thing? Well ... (in case you are too lazy to click on the link above) ... Joost is a P2P TV tuner software. You can receive a good number of TV stations with a decent quality.

Reanimating a PSS120

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Our old Philips MP3 clock died last week. It no longer works or starts up. In the past I was able to reset the unit to get it back to life, but this time the trick didn't do it. After reading on the net I saw many customers had to return their units with a similar problem, I guess there is a not so weird condition that reset does not cure.

I managed to open the unit without breaking it and I checked the battery that seemed ok. After unplugging and plugging back the battery the unit was working again. You will need the right screwdriver for the task as it has many small screws.

Losing the weekend fight

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Over the weekend I've lost several battles:
First one was against my TV computer. The Asrock motherboard died last week, so I bought a replacement but it was an Elitegroup VIA KM400-M. To make a long story short I tell you this mobo does not play right with my Nexus-S PCI card. Of course, figuring that out took me a good part of the weekend. I sent a support request to the manufacturer, but given the way the manage their website I'm afraid I am in for a big dissapointment.

Second, I turned to my desktop to scan some pages I realized that my Ubuntu upgrade to Feisty also did bring an annoying bug that made my Acer S2W 3300U scanner not to work properly. It turns out it is a new bug that can be avoided by using the scanbuttond application (weird but true, this daemon-like application prevents the scanner to be powered down which is what causes the bug). Finally I managed to get the work done, but I'm exhausted. Those of you with your shine Vista and the same scanner are not l…

Weird CUPS printing problem

Since I installed Ubuntu's Feisty Fawn my user impressions have been very good. However, some days ago I experience a weird problem when my system began to work erratically. I was not expecting it so it took me some time till I realized my filesystem was full. I did not understand why that was happening as the last time I checked there where more than 7GB of free space on that partition. But the first trouble sign was that print jobs where not printed.

After some confusion I realized I had 7GB /var/log/cups/error_log file. So that was the cause of my trouble. Inside the file I had millions of lines with the error message "Too many open files". It was clear there was a problem with the printing system.

I googled for that and I learned there were not one but two different reports of a similar problem. Just restarting the printing system was restoring the service (but not deleting the error_log file).

As soon as I removed the error_log file and restarted cups I was back on,…

OpenOffice fonts in Feisty

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A colleague of mine who tried the new Ubuntu 7.04 was not happy with the OpenOffice Impress tool (I'd say he was not very impressed) because certain pages were rendered using larger fonts that in the original page. This odd behavior was forcing him to patch slides that were ok for previous versions of OpenOffice.

I haven't experienced the problem myself, but I told him to have a look at Launchpad to see if there was a bug report on this and, if not, to file his own bug report. It turned out that a very helpful guy reported a similar problem, its cause and several suggestions to fix it.


It turns out there is nothing wrong with OpenOffice but last version of Ubuntu fails to do the right substitution with some fonts. This bug was not happening on previous Ubuntu versions though. As my friend's problem was due to the use of some TrueType fonts from Microsoft (a document migrated from PowerPoint) I suggested to install the package msttcorefonts and that fixed the problem.

eBay experiences

A few days ago I bought one item from a seller on eBay. Seller looked good. But two days after I sent my payment I got an eBay warning message telling me the seller's account has been canceled and advising me not to send any money. Unfortunately the money was already sent so there was not much I could do.

Checking the seller's account feedback page revealed that the flow of feedback messages had stopped as users cannot leave feedback on a canceled account (not sure this is a good idea) even if buyers are already getting what they paid for (or a brick in a box). Let me elaborate on this: Blocking a seller account should prevent the seller to do "any more harm" (ie. to sell any new item) but the feedback information is useful mostly for buyers, so you are here punishing the buyers if they cannot post feedback for a blocked account.

Some days later my product arrived ok and I was surprised when I can see I can leave feedback for this seller. In fact, it seems the seller i…

New life to the Traveling Salesman Problem

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I learned about this problem when I was a CS student: A salesman has to visit a set of cities and then returns home. The problem is to find the fastest/cheapest/shortest way of doing so. It is a NP-hard problem as the solution space is n! (for a n-city problem) that is impossible to be examined fully in a lifetime. It can be entertaining to do by hand, but there are many programs that may help you, like Concorde.
My interest for TSP was sparked as a possible solution to the optimization problem for the drawings made with my home-made painting machine. It is not a new problem but I was not aware of the best solution possible. I was lucky enough contacting Michael Trick who, right off the bat, gave me a nice and elegant solution.
I need to determine the right order for drawing a set of n lines but each line may be drawn in one direction or backwards. The solution to the problem needs to determine the drawing order of the lines plus the drawing direction for each one that makes the total d…

A good moment for a backup

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After doing a full backup of my trusty Ubuntu 6.06 system at home I decided to give it a shot to the new Ubuntu 7.04 (aka Feisty Fawn). I just decided not to be on the cutting edge and I did the install only after other users were reporting successful installs. So far I've updated a couple of my systems, the first one, an ASUS pundit worked like a charm and the graphics card was detected ok. The second system, with an ASROCK mobo with an ATI Xpress 200 graphics card was not so lucky and though the install worked I needed to do some black magic to get the graphics working at the right resolution and, more important, to get 3D acceleration.

Why is 3D needed now? Well, it is not really needed but after so many comments about all the "experimental" graphic features nicely included in the last Ubuntu I decided it will be nice to try it out (don't worry I am not posting any video to youtube).

The bottom line is that the new 7.04 feels a better Ubuntu than ever before, with a…

Graphics fun

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I was watching some paintings by Chuck Close and I thought of doing something in that direction but, of course, letting the computer do the hard work. I'm not yet finished as my initial goal was to create a GIMP plug-in (as Photoshop is not my thing), but I started using Perl and the GD library to get results like the one in the photo.
If you are interested in the perl code just drop me a line, it can work with any photo file (once you convert it to a GIF file). If you are familiar with GIMP plug-in creation you might want to help out finishing the work!

Time to switch away from Microsoft?

I have been testing Office 2007 and its new user interface. I did like it. But at the same time I did have some trouble finding some options (like the Save As ... --a hint: press the circle on the top left--) but the general feeling was that it should be easy to get use to it. However, another idea came to my mind: Over the years I have heard people from different companies saying that while OpenOffice was kind of ok they did not want to incur on the extra cost of re-train employees to learn how to use OpenOffice. The bottom-line now is that I find much easier to switch from previous versions of Microsoft Office to OpenOffice than to Office 2007. And I have not yet mentioned that file formats have changed too for Office 2007!!

This fact considered alone might be addressed by not switching to Office 2007 anytime soon. This is what all the companies I know are doing. But the second most amazing thing I can see happening is that no companies are switching to the much-hyped and secured Win…

Better video

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When I built the vertical plotter I mentioned one week ago I realised the video I was posting was not very good. I have received no complains but as I was painting something else over the weekend I decided to shoot it better and to fast forward a bit so as not to bore you to death. This is the result:


And before you ask me, this is the photo it is coming from:

Windows Log Files

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Today I needed to dig on a client's set of log files. I'm happy with text-based log files, but this time most of the research has to be done on Windows 2003 Server Event Logs. The problem is that in order to view this files you have to be running Windows 2003 Server and you have to use the Event Viewer program (or so I thought).

After having some trouble because I was not aware that Event Viewer is not happy when your files are read-only (as when you are handed over a copy on a CD-ROM) I decided it has to be a better way. Unfortunately, Event Viewer error message just said "wrong parameter" which is not telling you much about the cause of the problem.

A bit of Google and I discovered a software gem called LogParser, which can parse most of the different log files Microsoft OSs and applications create and, to ice the cake you can present your queries using SQL sentences on the command line. Many input and output formats are supported and it can also deal with your Apach…

New article published

April 2007 CircuitCellar #201 featuresanarticleaboutmyresearchontheinnerworkofECP bus that has beenusedinADEMCOalarmsformanyyears.

Note: Itisnotavailablefor general downloadbutforsubscribersonly.

Yet another shameless copy

Once I get one project running I tend to focus not on creating a polished version of it but on the next project to do. This time I am planning to build a 3D scanner for body parts (i.e. hands, arms, head) so I can create a polygonal version of them like an sculpture. The good news is that it's been done many times before: like this one, or this other. Some people even took the time to create an open source project to develop the software for such a homemade 3D scanner.

As I am yet in the early stage of the project I can only tell you that a line laser and a webcam (or photo or camcorder) are needed. The line laser is a laser that creates a line shape instead of a single spot. The cheapest alternative if you do not have one is to buy one of these straight line levels. Alternatively you can create a line laser from a laser pointer by inserting a cylindrical lens on the laser beam (any solid cylinder shape of plastic or glass can work here).

Once you have the laser line you also need …

Vertical Painting device

I've been working for a while on this project but now I've reached something close to a 0.1 version. I just suck at mechanical devices design. The system is copy of a similar project done at Cornell University and at école cantonale d'art de Lausanne but it happened to be more of a challenge that I assessed initially. Now that it is up and running I am using it to ease the process of transfering drawings to a canvas. I still have to discover why I am getting a 12% compression on the y-axis but in the mean time I can easily compensate for that.

I wanted to use a solenoid for the pen up and down control but I did not manage to get a reliable behavior so I am using a third stepper motor I ripped off from a floppy drive (I use two stepper motors for controlling the two hanging strings). I am using coal sticks to draw over the canvas and I've noticed that next version will need to include a compensation of the wear of the coal (as it gets shorter as lines are being drawn) t…

Regular Expressions in ... Visual Basic .NET?

A recent project required me to use Windows while I figure out how to write a driver for a USB-based stepper motor driver I am using. I decided to see how Visual Basic works in this new and glorified .NET version (my last experience was with VB version 6 and it was a pleasant one).

So I downloaded the free version (called Express) of Visual Basic 2005. I am doing so because this way any advice I can give to others may include the usual "you may want to use this software" without having to add "it will cost you so many dollars". Because most of the time I'm giving advice to my students it seems an ok approach to me.

The only "requirement" to use this software for an unlimited amount of time is to give away some personal info to Microsoft. I've found the deal ok this time.

The new version includes a browser window on the user interface that makes the loading time longer and I am sure I will be happier without it (maybe it can be easily disabled).

I was…

Timing belts and pulleys

When I started the project of creating my own version of Hektor I thought that the most difficult task would be something related with the software or the stepper motor controller, but I was wrong: The most difficult part has been finding the right hardware parts. More exactly, finding a local supplier.

While getting a USB 3-axis stepper motor controller on eBay was easy, even though it was coming from Australia it didn't take long. Finding the right toothed pulleys and belt it is being a nightmare, as local suppliers do not have "small size" elements nor a fast delivery. Should I have bought everything online I will be done now.

To be honest I was not even aware I would need that type of transmission system. My first impression was that it could be done with just some type of string, but after several failures I had to admit that toothed belts was probably the smart way to go. But then it was kind of late as I had the rest of components laying on my desk. After visiti…

Grayscale with ImageMagick

I use command-line ImageMagick's graphics file handling software. It usually rocks and it use to be easy and simple to use, for that I love it. However, I've been fighting now for more than one hour to get it right.

What I wanted was to convert to grayscale a set of JPEG files I had on a folder. There are a couple of annoying things with ImageMagick:

Once you use wildcard as the command source file (i.e. mogrify -resize 1024x768 *.JPG) then it seems to take a long long time to work. The reason seems to be the command reads and stores in RAM all the files BEFORE the magic starts. The result is a poor user response time (and sometimes an almost frozen system if you run out of memory and all the time is used paging). I use to change to use a for loop instead, with some "progress information" (i.e. for i in *.JPG; do mogrify -resize 1024x768 $i; echo $i " done!"; done )I do not convert to grayscale every week, so I cannot remember how to it. Here is when the tro…

Oracle SQL Developer

I needed to access some data on our corporate Oracle database server. Unfortunately, no information was given to me other that the PHP connection string. I had not idea about the table or view names either, so I tried to use a database management tool but lacking any previous knowledge about Oracle databases I look for what I've used in the past. I was quite happy with EMS Postgresql Manager and I learned they do have a simlilar product for Oracle databases, but after installing it I learned I needed to install SQL*Net software which I did not know where to get from.

However, a quick Google search lead me to another gem from Oracle: SQL developer and the word free captured my attention inmediately. It turns out it is a nice Java program that is available for a variety of platforms. I'm currently using it on Windows and Linux successfully (please note JDK >=1.5 is required).

Using this program I was able to learn about the tables on the server but not before I was able to disc…

eBay deals

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If you use eBay long enough you'll end up with some trouble. I guess the same is true wherever you buy your stuff. Sometimes things go wrong either with shipping or you get a nice DOA. My case is no different, after several good deals I've got a badly broken bycicle headlight (pictured on the left).

As it was a cheap item money was not a big problem, but still you feel you should get a fix, either in the form of a refund or a new item. The problem this time was the seller was not answering my messages. At this point I decided not to let him go without a fight. After 48 hours without an answer and checking in that seller feedback that not answering complains was his standard behaviour I filed a complain with eBay. However, eBay forwarded me to PayPal as the item had been paid using PayPal.

I thought that although I might not get the money back I would be educating the seller as I was guessing PayPal (through which he gets most of the payments) would force him to at least provide…

Digital camera madness

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I recently tried to learn a bit more about photography (I can recomend you this book). I've owned several film-based cameras over the years (both compact and reflex) and since 1996 when I bought a Casio QV-10 (not that I can recommend that battery eater) all of them have been digital units (Canon S10 and A520 and lately Panasonic DMC-FZ7, all of which I can recomend).

I was thinking to finally jump to the Digital Reflex bandwagon but I was waiting to get a better idea of that segment. But it seems the waters are not that clear. Although it seems that Nikon has settled with the so-called APS-C sensor size, Canon has mixed feelings and now it has three different sizes from full-size 35 mm sensor (like the one on EOS 5D) to APS-C size (like the one on 20D, 30D or 350D).

Why sensor size is important? Well, one of the reasons professional photographers have kept the reflex market going was compatibility. You cannot be compatible if you change the sensor size. And, it does not matter you …

File Uploads

Every now and then we all face a common problem poorly solved by today's applications: You want to send a big file to another person (or you want them to download it). For files several megabytes long (or larger) email is not the right tool (as email servers will reject send attempts larger than a few megabytes).

IM applications like MSN Messenger or Jabber might solve the problem, but only if you and your friend have that software installed and have a user account. But there is still another catch: This transfer happens between peers, so both you and your friend need to be online during the whole transfer.

To fix this, some applications like Pando can help, as they provide a multiplatform solution that does not require you both to be online while the transfer takes place. However, you both still need to download and install Pando client.

Upload centers allow you to upload files to be shared with the rest of the world. No user registration is required for some of them but some limits…