A Little Learning Goes a Long Way

Hidden Folder No More

2011-08-04T03:17:00.000+08:00

When a disk gets corrupted by a virus, some antivirus software change the attributes of the files and folders to "Hidden". I'm not sure why this is done. Anyway, it gets to be a headache sometimes. Imagine my horror when I was about to deliver a lecture saved in my portable harddisk only to find that I could not see not only the file but the whole folder itself!

To "unhide" a folder in Windows, type the following in the command prompt:

(Assuming H: is the directory where the hidden folder is)
H:\attrib -H -S "Hidden Folder Name" /S /D

Online Backup

2010-05-25T19:37:00.005+08:00

I discovered DROPBOX. And I'm happy I did. I almost threw away an IT news magazine that Eisen has torn to pieces. Good thing I took a look at the write-ups. If I hadn't I would not have read about free and convenient ways of backing up and syncing files.

I have two laptops, the old one is a desktop replacement at home and the other is my netbook which I carry around a lot. If I wrote a document on one of them I usually back up by writing an email to myself with the document attached. Cumbersome. And if I get lazy, I'll forget to do it and curse myself when I need the document elsewhere.

When I read about Dropbox I was amazed to find that it is cross-platform. MAC, Windows, Linux- can do. Free space is 2GB. If you need larger space you'll have to pay $9.99 per month for 50GB or $19.99 per month for 150GB.

You need to install Dropbox in each of the computers you want to have sync and backup access to. In Windows, a My Dropbox folder appears inside the My Documents folder.

Just drag your files to the My Dropbox folder and it will sync the copies in all your computers once they are online. Pretty neat.

Remember to save the modified file in the My Dropbox folder, though. Better yet, open it from there and save it there. If you have a copy of the file in a local folder it won't sync or backup unless you drag it again in My Dropbox.

Now I don't have to tear my hair and gnash my teeth when I've written a file in my desktop replacement. Simply by dragging it to My Dropbox I can have access to it anywhere.

Beeps when turning on your computer

2010-04-01T12:13:00.007+08:00

The PC won't turn on properly, instead you hear patterns of beeps. They are actually built-in diagnostic alerts. They can tell you what's wrong. I got this from http://www.pcstats.com/articleview.cfm?articleID=1223 while googling what those beeps mean.

No beep - no power, loose peripherals, bad motherboard or cpu
One beep - ok
One long, one short - motherboard problem
1 long, 2 short - video problem
1 long, 3 short - video problem
3 long - keyboard error
Repeated long - memory error
Continuous high, low - CPU overheating

I was trying to fix some old PC's in the lab since the students were complaining only 2 were working. Heard repeated long beeps in three computers - memory problem. Opened the hatch and placed the RAMS in a different slot and made sure they were snug and completely in.

Et voila! They worked!!!

Offsetting pages in OpenOffice

2010-02-27T17:34:00.003+08:00

I created a journal paper template following the fine advice of Dmitri Popov. A master document is ok but sometimes I just want to PDF that subdocument (journal article) right away with the corresponding planned pages.

Searching the web for offsetting solutions, I've got mixed results, none of them completely satisfactory.

Until... I found the best advice that came along. This is from OpenOffice.org's Tutorial on Page Numbering.

Summary
1. On the page where you want an offset page number go to the first paragraph
2. Right-click, select Paragraph then Text Flow
3. Check Insert, then With Page Style , then choose the page style you created if you have one on the scroll down menu
4. Then on Page Number, insert the start of the page number.

Composing a string and executing it in Matlab : preserving empty spaces

2010-02-15T23:57:00.005+08:00

Say you want to automatically open files which are named file001, file002, etc. Further suppose that these files are in a folder named d:\folder 1, d:\folder 2, etc.
Normally, you could use strcat to concatenate a string together with num2str. For example
FILE = strcat('file00',num2str(i));
But strcat will eliminate empty spaces so if strcat is used this way,
FOLDER = strcat('folder ',num2str(3)); % note the single space after 'folder'
the result will be
FOLDER ='folder3'.
To preserve the empty space, use square brackets instead:
FOLDER = ['folder ',num2str(3)]
Suppose you composed a string containing a command:
com1 = 'cd c:\folder 3\file001.jpg'
To execute the string use exec:
exec(com1);

Installing software in a netbook

2010-02-14T03:54:00.005+08:00

I love my netbook! It's light, it's cheap, and it has a large disk space. But when it comes to installing programs in it, I'm reduced to : 1) borrowing an external CD drive, or 2) downloading the software from the net.

There are two other ways: 3) share the CD drive over the network, and 4) create an ISO image of the CD. This last one I find very handy. I got this solution from btfx in Yahoo Answers.

Step 1. In a computer with a CD drive, create an ISO image of the installation CD. A compact freeware suggested is http://lc-iso-creator.en.softonic.com/

Step 2. Copy the ISO image in a USB drive.

Step 3. Insert the USB drive in the netbook and mount the ISO volume using DaemonLite http://www.disk-tools.com/download/daemon

Be sure to unmount the ISO after use.

The Problem with Technical Knowledge

2010-02-10T18:59:00.004+08:00

The problem with technical knowledge is that, technology marches by so fast that what you know now will become obsolete later, and quite quickly. If so, does it make sense to learn a technology at all? The Philippines is still a techonology "consumer" according to Dr. Roger Posadas in his talk on Science at "Beyond 2010". So will we be forever catching up?

I think there are still key concepts and skills to master (quantum mechanics for example) that will be relevant in the long term.

But I also think we can be ahead or be anticipatory. If we do research, we make our own technology and create new knowledge. In tackling research problems we come to grips with cutting-edge technology and create solutions where there are none.

I like to tell my students that a good research begins with a good research problem. The challenge really is asking the right questions.

What to do when SIP does not link with Scilab 4.1.2

2009-07-18T00:12:00.004+08:00

If you see the error message below when trying to activate SIP Toolbox in SCILAB...

Do this:

chdir(ImageMagickPath);
link('CORE_RL_magick_.dll');

Then reclick the "Toolboxes" button.

Reference:

http://www.scilab.org/contrib/index_contrib.php?page=displayContribution&fileID=146

DDR1, DDR2, SDRAM? How to determine a PC's memory when upgrading

2009-06-07T14:22:00.003+08:00

I have a desktop i bought in 2004. It's still working fine but I wanted to upgrade its 256 MB memory. But how do I know which type of RAM to buy? Without a manual, I took a look at the label of the existing RAM - it says there 256MB DDR 266MHz. But what is the maximum amount of memory I can insert?

I found this very useful application which can tell me what my RAM types are and more:

System Information for Windows by Gabriel Topala

www.gtopala.com

Note that each RAM slot has a maximum memory capacity and the motherboard has a total maximum capacity. It doesn't pay to insert 3 1 GB DDR's in a motherboard with a maximum 2GB capacity.

Upgrading Without a Recovery Disk

2009-05-19T08:13:00.002+08:00

My Lenovo 3000 C100 did not come with any Windows XP CD. Instead, the OS is embedded in the harddrive. I do not like this arrangement. First, it takes up precious space in the harddrive. Second, should the harddrive get useless, how do I upgrade?

And so with only 40GB (32 GB only with 8GB reserved by XP for Rapid Restore) my laptop quickly lost space. I bought an 80GB disk (the website says my laptop model can only accomodate up to 100GB and there was no such size in the market) and agonized whether I should install Mandriva or Ubuntu instead.

The decision to remain in XP was arrived at when I realized I would not be able to program in Matlab since my Matlab license is for Windows. Oh well, I can always dual boot. Scilab is fine but would need more improvements in image processing.

Fortunately, I found that it is possible to make a Windows Installer from such embedded OS. The original link seems no longer active. But here's a tip : In google, type How to Fresh Install Windows XP Without a Recovery CD. I thank profusely the one who figured this out.

What to do when your cellphone refuses to send and receive text messages

2008-12-16T15:22:00.003+08:00

After a year and a half of using my Sony Ericsson P990i it suddenly lost the ability to send and receive text messages. Turning it off and on again resulted in an "MsvServer" error. Canceling this message sometimes lead to intermittent bursts of queued SMS's. I also receive a message saying the SIM card is already full even if I've erased much of its contents.

What worked was the suggestion of my friends who experienced the same problem.

The solution - MASTER RESET. Just make sure you've backed up all your contacts and other important data from your phone.

Master Reset is found in the Control Panel->Device menu.

Inserting images as background for OpenOffice Calc graphs

2008-08-13T12:11:00.004+08:00

(Thanks to Eduardo David Jr. for tip.)

In verbatim, Ed's advice:

"1.)Click the plot ONCE
2.)Choose Area (see attached image)

3.)Go to Bitmaps tab, then choose Import
4.)Select the image
5.)Double click the plot then choose Chart Area
6.)Under the Area tab, choose Bitmap
The imported image should appear in the list :D"

General Comments on the handwritten text activity (morphological operations) AP 186

2008-08-07T09:12:00.000+08:00

I was delighted to find several of you succeeding in getting the outlines of the handwriting right. I noticed several common mistakes though:

1. Morphological operations work on white blobs. Most of you had the background on white and the handwriting in black. Such image must be bit-inverted (0 becomes 1, 1 becomes 0). So even if you did opening and closing with the intent of fixing the handwriting, the operations opened and closed the background.

2. The choice of structuring element is critical. Most of you simply used a 2x2 struct element even if this was not appropriate. Some of you wisely chose a 4x1 element since most handwriting have vertical elements. I would suggest that if the handwriting is slanted, use a slanted structuring element as well.

Finally, a tip. If the processed handwriting is fat, you might want to use thin to make it one pixel thick.

Image Histograms in Scilab

2008-06-24T11:17:00.000+08:00

Two solutions were found by my students to display the histogram of a grayscale (or indexed) image.

The first solution is a code written by Jeric
//Jeric Tugaff
//Histogram
im=imread('grayscale.jpg'); //opens a 24 bit image
im=im(:,:,1);imwrite(im(:,:), 'gs.jpg'); //converts to 8 bit grayscale
imageim=imread('gs.jpg');
val=[];
num=[];
counter=1;
for i=0:1:255
[x,y]=find(im==i); //finds where im==i
val(counter)=i; num(counter)=length(x); //find how many pixels of im have value of i
counter=counter+1;end
plot(val, num); //plot. :)

The second was found by Jorge, a built-in function

histplot([0:1:255],c);

where c is the image variable.

Collective comments on Activity 1 AP 186

2008-06-14T00:23:00.000+08:00

AP 186 08-09 Class:

Most of you got the technique right. 10 point for those with correct reconstruction. 11 points for those with convincing overlays. There are a few who forgot the following important details, though:
1. The journal source - a number of you didn't cite what journal and paper they got the graphs from.
2. Collaborators - some of you forgot to mention who helped you. Please tell if you did it independently. Part of the learning is learning from each other. If you're not certain, ask around. If you're certain, share.
3. Details on how you got your graphs - some of you had no explanations.
4. Self-evaluation - remember you give your grade. If i think you got lower or higher than what you deserve I'll change it.

Progressive scan camera ideal for image processing

2008-03-02T17:25:00.000+08:00

Choose a progressive scan camera for detail-sensitive research applications. Interlaced cameras suffer from twitter and must be de-interlaced. De-interlacing causes blurring in output image. On the other hand, progressive scan cameras will send signals "progressively", as in horizontal line per line and not alternatingly.

Opening a new figure window in SciLab

2008-02-27T04:40:00.000+08:00

To open a new graphics window in SciLab use
h = scf(fig_num).

Reading "dates and time" in Matlab

2008-02-23T16:26:00.000+08:00

If given a .txt data file with date entries enclosed in "quotes", open in xls and save as .csv. In Matlab call with textread and for the column corresponding to the date, use the format %q.

Counting the incidence of a name

2008-02-23T10:06:00.000+08:00

In OpenOffice spreadsheet, suppose I want to count how many times a name appears, I found that one can use the countif function with the following syntax:

=countif( <range of cells to look at>;"="&<pattern>)

can be

"Name"
or
a cell such as
F65.

Caveat: This function is very strict with pattern matching. A space at the end of the name will result in no match so be careful.