Fatih's weblog

Sis

2011-08-17T22:12:00.003+03:00

ImageMagick montage (creating picture collages)

2010-09-12T00:30:00.013+03:00

Using Gimp takes much time unless you are familiar with layers etc. Picasa 2 in ubuntu 9.04 does not give permission to customize the collage maker's options (like background color, positioning, gap etc.). So ImageMagick is a good choice to create collages.

An easy way of creating collages with ImageMagick:

montage *.jpg collage.jpg

or consider there are plenty of files in a directory named such as xy.jpg, xy1.jpg, xy2.jpg, xy3.jpg, ..., you can specify the filenames to be montaged (also border type and color, etc.) as:

# montage filesToBeMontaged -theBorderType # -theBorderColor # -theGapBetweenPictures +#+# resultantCollage
montage x{y,y1,y2,y3}.jpg -border 5 -bordercolor darkyellow -geometry +2+2 collage.jpg

Here are the other very useful examples.

DIY: Subaru Forester Spark Plug Wire Set Replacement

2010-08-12T16:17:00.003+03:00

I replaced the old OEM spark plug wire set with Exact OEM fit of NGK FX54 8772 Wire Set.
Although the old wire set resistance values were still in bound of the spec, i decided to change them since they were very close to the upper limit. Here are the resistance values per cable:

Wire order:
rear of car
3 4
1 2
front o car

Wire resistance of my forester and Ref. values:

Wire resistance of my Forester: Wire resistance specs:
[kOhms] [kOhms]

#1 cord: 12.3 7.40 — 17.27
#2 cord: 11.6 6.24 — 14.56
#3 cord: 11.8 6.54 — 15.25
#4 cord: 14.6 6.59 — 15.37

Replacement was very easy it took about 10 minutes. NGK indicates the cylinder lead ID on each cord.
Start with putting the spark plug part of cord first and then continue with following the same way with the old wire, that is it.

I bought wire set from www.ClubPlug.net of CA. They got it from NGK dist. on Thursday and sent to Toronto by the Prulator next day shipping at around 4:30 pm. It was at the hotel by 10:30 am. I should send my thanks to them, of course also to my friend Murat who brought them to me.

PyWeek.org

2010-07-24T02:26:00.007+03:00

Python Open Dynamics Engine (PYODE) Installation on Ubuntu

2010-07-15T23:03:00.009+03:00

PYODE installation failure occurred during "make install" on ubuntu.
1 - $ sh autogen.sh
2 - $ ./configure
3 - $ make
4 - $ make install -//failed in ubuntu

At this point open Synaptic Package Manager (SPM) and search for "pyode".
It should find python-ode-doc and python-ode.
Check them to install.
Apply changes (Installation starts automatically).

Now, ode in python can be imported successfully.

Again using SPM, install "pygame" package.

Once pygame installed 2pendulum.py can be executed.

Calling a python script from python shell:

#import needed library

import subprocess

child = subprocess.Popen("python 2pendulum.py", shell=True)

Kıbrıscık'tan Bolu'ya

2010-07-05T22:50:00.000+03:00

DIY: Subaru Forester Front Hub Bolt Replacement

2010-07-05T21:48:00.004+03:00

Start of the driver side axle boot replacement was ended with replacement of the hub bolt. I broke it while removing the wheel nut. That was easy to replace took about 20-25 minutes.

Remove brake center and fix with a plastic holder.
Remove disk.
Remove small 10 mm nuts.
Replace broken hub bolt.
Do not try to fix completely before installing the wheel. It will be pulled by the wheel nut.

Bug in MATLAB?: Increment shortcut in a loop (ex. ++i;)

2010-06-29T20:14:00.008+03:00

Today, i used an increment shortcut in a MATLAB simulation loop. Surprisingly i realized that MATLAB accepts the increment shotcut (++variable) without any warning but it does not increase the variable's value in the loop, it remains the same as the value that was initialized to.
However as an active Octave user in Ubuntu, this usage of the shortcut was just a programming practice for me and it always worked fine. Actually, as far as i understood from the MATLAB Central, these shortcuts are not implemented in MATLAB. But my point is not the absence of implementation, my point is the absence of warning (or error might be in this case) on the usage of the unimplemented increment shortcut.
It can be called as a bug because a permitted shortcut usage does not work properly at least.

Screeshot from Octave:

Screenshot from Matlab:

DIY:Subaru Forester CV Boot Replacement

2010-05-29T20:07:00.004+03:00

1.Removal of CV shaft:
1.1Remove CV nut: Use 32 mm socket.
1.2Remove lower ball joint: You may use pickle fork to apply leverage between spindle and the ball joint. Also ball joint puller may be used . Some people apply some grease to the fork not to break ball joint plastic boot. [!] I did not need any fork or puller. Removed 14mm pin, made a moment arm with two socket expansions and apllied moment between the spindle and the ball joint [See Collage[3]].
1.3Break free the axle from the spindle.
1.3.1[!] For exact straight pull of axle, i fixed the disk to the right side with a rope.[See Collage[5]]
1.4Pull the whole axle shaft.
2.Replacement of the CV Boot:
2.1Remove CV Boot:
2.1.1Use pinch plier to remove big pich inside and the smaller one at the engine side.
2.2Greasing:
3.Install CV Axle:

References:
[1] Removal of CV shaft
[2] subaruoutback.org DIY forums

Collage[1]

Collage[2]

Collage[3]

Collage[4]

Collage[5]

Collage[6]

Collage[7]

Collage[8]

Collage[9]

Inline defined function in OCTAVE works faster! (Was slower in MATLAB)

2010-05-19T21:19:00.001+03:00

Previous example in MATLAB was concluded the Inline defined function was working slower than the same function defined in a ".m" file .

But if you try the same example in GNU Octave 3.2.2 you'll surprisingly see that inline defined function in Octave works faster.

On the other hand, it was not the aim of the work but Octave works faster than MATLAB for this case.

DIY: Subaru Forester Steering Rack Boot Replacement

2010-04-03T21:09:00.019+03:00

Remove the old boot:

Using a small pliers or a screwdriver remove band from boot. Band can not be removed properly, i had to cut it since it was melded. Here, be careful to keep pipe connections free from pliers (or what tool you are using) while removing the band.

The small clip can be used again if you remove it carefully. All you have to do is to press to both sides with a pliers.

Install new boot:

I prefer removing the tie-rod end to put the new boot. Im not sure but if you have a lift, you may remove inner tie-rod without dealing with rod end.

Update: I found a very very helpful Steering rack boot replacement thread on subaruoutback.org. As i declared above, it also implies the need of tie-rod end removal.
But today i have seen that it is not really needed, if you jack up the vehicle. It is possible to break the locking nut with two 19 mm combination wrenches and go on twisting the rod and break it into two pieces. After removing the 19 mm nut you can replace the boot.

Some lessons learned: The old clip did not fit to the boot. Consider using some plastic fold locking cuff. And fix the small end of the boot after installing tie rod. If you fix it before it will twist and break.

Some pictures:

Gnome Commander on Ubuntu

2010-03-31T02:21:00.007+03:00

As a Total Commander fan, i also use Gnome commander on my Ubuntu laptop. You can directly start many programs from Gnome Commander command line. Write name of the prog. and press enter, that is it. The cursor not necessarily to be on command line. Just start typing it.

R-Project Syntax Highlighting by Gedit

2010-03-31T01:50:00.012+03:00

Gedit text editor highlights code scripts in many programming languages. Also works for Octave and R-project.

Swarms of Robots as Mine Search & Destroyers

2010-02-23T00:35:00.003+02:00

The main subject of this work is the design of collective behaivour of robots to perform mine search on an arbitrary area. We consider that the mine searching team consist of the below members:

Leader
Data Collector
Search robot
Destroyer (Self destruction on the mine)

Intelligence of the robots:

Search team have the below properties/abilities

Search algoritms
Determination of Leader of Colony
Mission Planning

Leader: Responsible from managing the health of the mission. Has ability to rework on the mission planning during the mission if needed. Also ability to assign itself as search, data collector or destroyer robot. It processes the real time data of the mission and choose the best option for the health of the mission. Also communicates with the base camp.

Determine the search area.
Work assignment.
Keep all the other robots away from the determined mine before destruction occurs.
Put all the team members into standby mode during destruction at which they are relatively safe from the explosion/destruction.

Search Robots: Responsible from searching and passing the “mine determined” message to the Data Collector. Have excavator mechanism.

Destroyers: Self destruction occurs as the activation of mine is performed. For this issue, destroyer robots include a mine destructor mechanism. Also destroyer robots have some excavator mechanism around their body to handle the deeply placed mines. End of mission is reached when the last destroyer successfully performs its work or the mission time period ends.

Data Collector: As in many of the systems in general, here one of the robots work for collecting the realtime mission data from the search team members.

Possible Scenario:

Kıbrıscık - Karagöl

2010-02-23T00:28:00.002+02:00

Lat - Lon: 40.357729,31.928158

Beypazarı - Uşakgöl Yaylası

2010-02-23T00:22:00.002+02:00

Lat - Lon: 40.344909,31.929166

Beypazarı - Kirazyanı Yaylası (1600m MSL)

2010-02-23T00:16:00.002+02:00

Lat - Lon: 40.341703,31.948221

Beypazarı - Ahlatlıbel Geçidi (1640m MSL)

2010-02-23T00:09:00.001+02:00

Lat - Lon: 40.317404,31.957362

Beypazarı - Uşakgöl Köyü

2010-02-23T00:04:00.001+02:00

Lat - Lon: 40.29064,31.925669

Beypazarı-İnözü Vadisi - Kozalan yaylası

2010-02-22T23:54:00.004+02:00

Lat-Lon: 40.253099,31.905971

Patrolling Robots

2010-02-14T03:41:00.010+02:00

Belkide eski mayın patlatma aracına yakın kavramlardan birisi "Patrolling Robots" olabilir.

Özellikle kar üzerinde duran kafamdaki araca (böcek diyelim) gayet yakın.

[1] Patrolling Robot: Tekerlekler güzelmiş

[2] Kar üzerinde: Tesbih böceği gibi

[3] Dahası burada [Robot.Watch]

Birde bu robotlar biraz daha sofistike olsalar ve birbirleri arasında haberleşebilseler. Hatta görev dağılımı yapabilseler. Bu durumda iş Swarm Robotics ve Swarm Intelligence'a doğru gidiyor.

Kaynaklar:

Wikipediaya'da Swarm Robotics.

Artifical Intelligence ve Robotics ile ilgili bir bl0g.

Testing "inline" function speed in MATLAB

2010-01-21T02:20:00.005+02:00

A function defined as a seperate m-file works faster than inline function of MATLAB.

DIY: Subaru Forester Engine Coolant Water Container Clean&Refill

2010-01-20T21:23:00.013+02:00

As a standard normal procedure, i was adding some front window cleaner solvent to my forester. I was lucky that i have examined my fault before running engine: I filled the wrong container. Yes, it was the engine coolant container that filled up to head. So what i have done, after some phone call with my older brother Bülent (Like anytime that i have to take a very fast and brillant answer) was removing and cleaning the coolant water container.

Eigenvector Calculation with MATLAB vs Mathematica

2009-11-05T13:05:00.011+02:00

We have realized that eigenvector calculation for a square matrix whose eigenvalues are all zero must be done by symbolic toolbox in MATLAB. Otherwise MATLAB gives the wrong answer. Or, you can use Mathematica instead. Since Mathematica is able to calculate eigenvectors numerically for this case.

Here is the example:

Consider such a 6x6 square matrix:

In MATLAB, try to calculate eigenvectors numerically:

%% Eigencvector calculation:: Directly numerical

A1=[0 0 0 0 1 0;0 0 1 1 0 -1;0 0 0 0 0 0;0 0 0 0 0 0;0 0 1 0 0 -1;0 0 0 0 0 0];

[v1,l1]=eig(A1)

Matlab gives eigenvectors as:

which is wrong!.

However by symbolic toolbox:

%% Eigencvector calculation: Using symbolic toolbox

A2=sym([0 0 0 0 1 0;0 0 1 1 0 -1;0 0 0 0 0 0;0 0 0 0 0 0;0 0 1 0 0 -1;0 0 0 0 0 0]);

[v2,l2]=eig(A2)

That's now ok!

%% Cross checking with "null space" concept

%Altough we define matrix numerically, null space of A1 however gives numerically true eigenvector familiy:

null(A1)

And finally here is the Mathematica screenshot:

Mathematica calculates successfully:

How to create mplayer playlist in Ubuntu

2009-11-04T17:16:00.005+02:00

1 - Open a terminal within your directory that includes the media files ("mp3" for this case) to be added to the playlist.

2 - Use find command with -name option to list files (lists recursively by default) and send this list into your "playlistName.m3u" ("Totem Player" in Ubuntu considers .m3u files)

Here is the script: (GNOME Terminal 2.28.1)

$find -name '*.mp3' >playlistName.m3u

How to read Binary Data File in C (Sequentially)

2009-10-15T14:05:00.005+03:00

Exactly two lines have to be changed from ASCII file mode given here.

Differences from ASCII mode:

1 - Additional "b" for fopen()

2 - Usage of fread() instate of fscanf

*/
...
fp = fopen(i_filename, "rb"); // read a binary file ("r" and "b")
...
/* loop until all data keep into array */
while( (!feof(fp))){
//fscanf(fp, "%f", &value); you can not use this any more for binary files. Now you have have to use fread()

fread(&value, sizeof(FP32), 1, fp);

...
}

Türkçe Karakterlerin Unicode karşılıklarını bulmak ve kullanmak

2009-08-19T11:20:00.004+03:00

Start->Run->charmap ile Character Map açılır.

Buradaki harflerin unicode karşılıkları Character Map penceresinin en sonunda "U+0130" şeklinde gösterilir.

Bu unicode karakteri yazarken ortadaki "+" işareti kullanılmaz be başa bir "\" işareti koyulur. Örnek: I harfinin unicode'u U+0049 dur, \u0049 şeklinde kullanılır.

Kendinden enerjili eski mayın arama / patlatma aracı

2009-08-18T00:28:00.006+03:00

"Self energized" robotlara baktım biraz ama cok birşey bulamadım. Birtane "spring loaded" kendi kendine zıplayan bir robot var. Neyse, mekanizması nasıl olur bilemiyorum ama birileri herhalde biliyordur.

Merak ettiğim konu şu:

Küre şeklinde olan, toprakta ve taşlık arazide hızlıca ilerleyebilecek minik keskin uçlu birrçok ayağı bulunan bir araç yapılabilse. Bu aracın boyu da normal bir insan eli kadar olsa. Ayrıca, üzerindeki sıkıştırılmış yay mekanizmalarından güç sağlasa (1km kadar ilerleseler yeter mi?) ve ucuzca üretilebilse. Bunlardan birçoğu (mesela 1000 tanesi) mayınlı olduğu düşünülen yada bilinen araziye salınsa. Acaba mayın temizlemede veya mayından korunmada bir yöntem olabilir mi?

Neyse bu arada araştırma yaparken birazcık da self energized robotlar ve uzun süredir merak ettiğim yay mekanizmalarına da bakarız. Bilen anlatsın. Mekanizmalar kitabında var mıdır ki?

How to add an image to a JPanel

2009-08-17T15:01:00.007+03:00

In case of using Netbeans IDE Palettes for GUI building, in order to insert an image into JPanel, you have to change the layout of panel to "Border Layout". Then you have to use a JLabel to pass the image into JPanel.

I have tried many ways but this worked fine for me:

ImageIcon picturetoInsert = newImageIcon("C:/images/anyimage.gif");

JLabel label = new JLabel("",picturetoInsert,JLabel.CENTER);

pPanel.add(label,BorderLayout.CENTER);

How to read (ASCII) data file in C

2009-07-28T02:23:00.009+03:00

/*Function that reads the data file into an array and returns a pointer that points to this array of FP32*/

FP32* readData(const char *i_filename){

FILE *fp;
fp = fopen(i_filename, "r"); //open file , read only
INT32U numElements = 0;
FP32 value; //keep value at pointer position
FP32 *array=NULL; //set to NULL because of realloc
/* loop until all data keep into array */
while( (!feof(fp))){
fscanf(fp, "%f", &value);
array = (FP32 *) realloc (array,(numElements+1) * sizeof(FP32 *));
array[numElements++] = value;
}
/* shift array and add "size of array" to its first element
since there is no way to get size of an array from its FP32 pointer*/
INT32U i;
array = (FP32 *) realloc (array,(numElements+1) * sizeof(FP32 *));
for(i=numElements;i>0;i--){
array[i]=array[i-1];
}
array[0]=numElements;
/* close file */
fclose(fp);
return array;
}

DIY: How to Replace Subaru Forester Spark Plugs

2009-07-17T18:57:00.013+03:00

It has been 30K [km] and almost a year since my last spark plug change (That was first for me). So, today i bought four NGK Spark Plugs from one of (Official Service) Subaru Dealers in Ankara and replaced them.

For now this post is copied as is from Wikimechanist.
The upcoming posts that can be named as "mechanic" will be posted only to Wikimechanist.

1 - Remove air filter elements going to the air filter to get free space:

2 - Remove Spark plug cables:

3 - Remove Spark plugs with suitable socket. That is 16 mm.
Also you'll need torque wrench to tighten with proper torque. If you have not one. Turn spark plugs 1/2 to 1/4 turn after contact occurs.

The previous change was 30K [km] before. You can see the old and the new spark plugs. The clean one is new of course. It must have 1 - 1.1 mm gap. If not adjust it.

For the driver side plugs, you need to remove window washer water container.
But not fully removal is needed. You may fix it with some elastic holders after turning it a little. You may have enough space to handle replacement of spark plugs.

Update (02.01.2010) some pictures for driver side plug removal:

Good luck.
It is pretty easy. Just half an hour for me.

Forester arka camındaki örümcek ağı

2009-07-10T12:50:00.005+03:00

How to Change Rear Differential Oil of Subaru Forester

2009-07-09T14:17:00.010+03:00

Step 1: Lift up vehicle a little bit. Since you'll need some free space to handle 24'' wrench to loosen the differential 1/2" plugs.

Step 2: Loosen the upper plug first. If you can not be succeed still you will have a chance to call mechanic. Otherwise the lower plug will drain the oil.
The oil will start to bleed a little. Put your waste oil container below the plug.

Step 3: Now loosen the lower plug and drain the full oil.

Step 4: Differential needs 0.8 liters of 75-90 GL-5 performance level oil. You may need a plastic pipe to reach differential. I choose a plastic container and put a pipe on it. Fill up the differential till it starts bleeding from the upper plug hole.

Tightening torque for the plugs: 49 NM
Thnx to:
subruforester.org

Windows Media Player için Playlist oluşturmak

2009-06-26T08:51:00.005+03:00

Windows Media Player için Playlist oluşturmak:
External HDD de tuttuğum müziklere ayrı ayrı playlist oluşturmak için kısaca şu ms dos komutlarını kullanıyorum:

Örneğin:

1 - hdd de music dizini olsun. Buraya cmd komutu ile command window aç.

2 - playlist oluşturmak istediğin dizine git "cd dizin_ismi"

3 - dir /S (recursively) /B (without headers) *.mp3 (sadece mp3 leri al) > ../playlist_ismi.m3u (bir yukarıdaki dizine "palylist_ismi.m3u" dosyası olarak kaydet)

4 - palylist_ismi.m3u üzerine çift tıkla WMP açılır çalmaya başlar.

Windows'ta Netbeans 6.5 ile C geliştirme

2009-01-22T15:24:00.007+02:00

Netbeans-6.5'i indir.
Netbeans-6.5 icin c/c++ development package'ini indir.
Netbeans-6.5 i kur.
Netbeans -6.5 icin c/c++ dev. pack'i kur.
MinGW-5.1.4'u indir ve kur. -> gcc for windows
MSYS'i (Not: Bu direct link değil, direct link versen de sonradan kırılır.Buradan MSYS yi kendin bulacaksın) indir ve kur-> kurulumda MinGW'nin yerini soracak ve Netbeans icin gerekli gmake'i kuracaktır.
Artık Netbeans, C/C++ projesi oluşturulmak istendiğinde otomatik olarak C compiler ve tools ayarlarını yapacaktır.
Eger hala make icin ne kullanacagını bulamamışsa : "dizin ismi":\msys\1.0\bin\make.exe'yi kullanmasını sağla.

SUN SOLARIS 10'a gcc ve ada compiler kurmak

2009-01-17T01:15:00.004+02:00

Makinada internet baglantisi varsa:
Adım 1:
# pkgadd -d http://blastwave.network.com/csw/pkg_get.pkg
eğer pkgadd şu hatayı verirse:
ERROR: attempt to process datastream failed
- bad format in datastream table-of -contents
http://www.blastwave.org/pkg_get.pkg dosyasını indir
ve

# pkgadd -d pkg_get.pkg

komutu ile kur.

Adım 2:
# gedit /opt/csw/bin/pkg-get.conf
komutu ile config dosyasını aç ve mirror linkini şu şekilde değiştir.
url = http://blastwave.network.com/csw/unstable

Adım 3:
gcc ve gnat'ı şu komutlarla kur:
# pkg-get install gcc4core
# pkg-get install gcc4ada
pkg-get'in faydası: 1 - tek komutla indirip kurmak.
2 - dependency'leri kendisi bulur ve kurar.
Adım 4:
gedit editorü ile profile dosyasını aç:
# gedit .etc.profile
ve dosyanın sonuna şu şatırları ekle.
PATH=${PATH}:/opt/csw/bin:/opt/csw/gcc4/bin;export PATH
-- dikkat ederseniz PATH'e /opt/csw/bin dizinini de eklemek gerek. Çünkü gcc "gas"'ı kullanıyor.
Böylece birdahaki açılışta gcc, gnat ve pkg-get fonksiyonlarına direkt ulaşılabilir.

Makinada internet baglantisi yoksa:

Bu durumda ilgili packagelari da iceren su dosyalari blastwave.org'dan indirip pkgadd ile kurmak gerekiyor:

libiconv-1.9.2-SunOS5.8-i386-CSW.pkg.gz

gcc4corert-4.0.2,REV=2005.09.29-SunOS5.8-i386-CSW.pkg.gz

gcc4core-4.0.2,REV=2005.09.29-SunOS5.8-i386-CSW.pkg.gz

gcc4adart-4.0.2,REV=2005.09.29-SunOS5.8-i386-CSW.pkg.gz

gcc4ada-4.0.2,REV=2005.09.29-SunOS5.8-i386-CSW.pkg.gz

common-1.4.6,REV=2008.04.28-SunOS5.8-i386-CSW.pkg.gz

binutils-2.17-SunOS5.8-i386-CSW.pkg.gz

Project ElectriCityCar

2008-01-22T00:53:00.002+02:00

This is an upcoming project that seems to take most of my future entries on wikimechanist . I have just started to make literature servay.
Currently, i am preparing a Google document to be shared with the people who are interested with this project.--Please send comments if you are interested--
An important note: I have discussed this project with my older brother Yalçın, who is an electricity and mechanic man, finally i took a promise for his help. This is important, that is the first time that i have succeeded to induce him to work on my project :).

My Nokian WR G2 Winter Tyres

2007-11-14T19:55:00.001+02:00

I have bought four Nokian WR G2 tyres from ANKARA/TURKEY last week.

As you know, these tyres have asymmetrical inside/outside tread pattern. My question comes here; “For these types of tyres do you produce left and right ones explicitely?, so do i need to buy left and right WR G2 tyres?”. I know that directional tyres carry markings on the sidewall which indicate the correct direction of rotation and asymmetrical tyres carry markings to identify the inner- and outward-facing sides. Note that Some tyres are both asymmetrical and directional (Dunlop has). Nokian WR G2 has only inner-outer side markings, on the other hand there are some arrow like lines which i thought that these may be directional indicators. Although i have searched the nokian's web site i could not get the correct wordings that guaranties the wr g2's are not directional.

So i have asked this question to my dealer and they answered “No, these are only outside-inside, not directional tyres.”

As a result they said that it is not important which side you have fitted the tyre (left or right).

But as illustrated in the below figure (Figure 1) the patterns differ for the right and the left side, Is it acceptable or do we need to use left-right tyres?

Figure 1 Illustartion of my car and the Nokian WR G2 tyres. As can be seen, the patterns differ for left and right side of the car. Is it acceptable?

2007 METU-DownTown

2007-05-12T22:48:00.000+03:00

Dağ bisikleti ile ilk madalyamızı aldık...
Umut ile katıldığımız ODTÜ'de düzenlenen dağ bisikleti yarışında 3'ncülüğü aldık. Artık kondisyonumuzu artırıp yeni yarışlara katılırız belkide...

Bu nasıl çalışıyor?

2007-01-26T23:37:00.000+02:00

Bu nasıl çalışıyor? yayın hayatına adım attı...
Şimdilik sizlere gerçek bilgi sunmaktan çok nasıl bir blog olacağını anlatamakla meşgul.
Sizlerden beklentimiz merak ettiğiniz konuları yazmanız.
Eğer o konuda bilgimiz varsa veya bilginin nerede olduğunu biliyorsak Bu nasıl çalışıyor?'a ekleriz.

Studded winter tyres

2007-01-26T23:17:00.000+02:00

Wikimechanist's first entry...

VRML (Virtual Reality Modeling Language)

2007-01-08T13:33:00.001+02:00

Web'de bulunabilecek en iyi vrml kaynağı, ayrıca underwater systems konusunda da geniş kapsamlı kaynak:
brutzman

Multidimensional Vector Product

2007-01-05T09:30:00.002+02:00

It is shown that multi-dimensional vector product is only possible in seven dimensional space.
You can download the paper from the link below.
[Multi-dimensional vector product]

C++'da ifstream kullanmak

2006-12-29T14:39:00.001+02:00

C++'da ifstream'in boş satırları okumaması için kullanılmasını önerdiğim kod [Bkz. C++'da fstream kullanmak] eğer formatted data dosyasında negatif sayı ile başlayan bir satır varsa o satırı ihmal ediyor.
Bundan kurtulmanın da yolu var. Biraz çirkin gibi ama eğer komentlediğiniz satırlar '-' karakteri ile başlamıyorsa şimdilik kullanılabilir.

örneğin aşağıdaki kod formatted data dosyasında '%' karakterini koment satırı olarak kabul ediyor ayrıca negatif sayı ile başlayan satırları da hatasız okuyor.
Not: Bunu kaynaklarda kolayca bulabilirsiniz. Entry'i yazma sebebim daha önce verdiğim kodun muhtemel hatasını anlatmaktır.

if(file_to_read.peek()!='-'){ //satır başında negatif sayı yoksa
if(!isdigit(file_to_read.peek())|| file_to_read.peek()=='%') {
file_to_read.ignore();
continue;
}
}

Derivative of a vector function of a constant length

2006-12-25T01:35:00.000+02:00

Let v(t) be a vector function whose norm is constant, say, |v(t)|=c.
Then
|v|^2=v.v=c^2,and
(v.v)'=v'v+vv'=2v.v'=c'=0 by differentiation.
This yields the following Result.
The derivative of a vector v(t) of constant norm is either zero vector or is perpendicular to v(t).
Since Dot product of two nonzero vectors are zero iff they are perpendicular to each other.
[Erwin Kreyszig, Advanced Engineering Mathematics 8th eddition. Page 426.]

Inline in C++

2006-12-21T23:58:00.001+02:00

The double vector sorting and addition functions are defined as inline using the inline keyword.

Code:
//MyMath.h
inline int sort_vector_inline_new(vector<double>& v){ //new inline
sort(v.begin(),v.end());
return 1;
}
inline int add_inline_new(int a,int b){
return a+b;
}

Result:(Speed test)

Inline Function in C++ (vector sorting speed test)

2006-12-21T22:36:00.001+02:00

Now it differs from addition...
"double" vector sorting with class defined function is faster than inline function defined in header file. See the below test.

Test:
Copy and paste the below codes to your previous test project files to add vector sorting capability.
İf you want, change the name of the class "Add" in "MyMath.h". Since it contains also sort() function now
Do not forget to include "vector" and "algortihm" for dealing with vector and its sort() method.
Here is the additional includes for changed files
#include"vector"
#include "algorithm"
//put this code to "MyMath.h" int sort_vector_inline(vector<double>& v){ //defined inline sort(v.begin(),v.end()); return 1; }
int sort_vector_class_def(vector<double>& v);

===============================================

//put this code to "class_def.cpp" int sort_vector_class_def(vector<double>& v){ //defined inline sort(v.begin(),v.end()); return 1; }

===============================================
//All of Main.cpp is given here.(lots of changes). //Filename:Main.cpp
#include "MyMath.h"
#include "stdafx.h"
#include "vector"
#include "algorithm"

using namespace std;
void main()
{
DWORD startTime,endTime,difTime;
vector v,v1;
int a=1;
int b=2;
int c;
Add testAdd;

cout<<"double vector sorting..."<<"\n";

//fill vector with random numbers
for(int j=0;j<1e7;j++){
v1.push_back(rand());
}
startTime=GetTickCount();
testAdd.sort_vector_inline(v1);
endTime=GetTickCount();
difTime=endTime-startTime;
cout<< "it took "<//fill vector again since sorted vector sorting is much more faster

for(int j=0;j<1e7;j++){
v.push_back(rand());
}
startTime=GetTickCount();
testAdd.sort_vector_class_def(v);
endTime=GetTickCount();
difTime=endTime-startTime;
cout<< "it took "<
cout<<"addition..."<<"\n";
//use function defined in other cpp file
startTime=GetTickCount();
for(int i=0;i<1e9;i++){
c=testAdd.add_class_def(a,b);
}
endTime=GetTickCount();
difTime=endTime-startTime;
cout<< "it took "<startTime=GetTickCount();
for(int i=0;i<1e9;i++){ style="color: rgb(0, 0, 0);"> c=testAdd.add_inline(a,b);
}
endTime=GetTickCount();
difTime=endTime-startTime;
cout<< "it took "<}

===============================================

I changed the order of functions in main file to see if there is a difference in speed.
It is same for the addition. Still inline function works faster.
Let's see what happened for vector sorting (below pictures).

if you change the order of function calling sequence, inline function for vector sorting works faster.
So we could not say anything about speeds yet.

Inline Function in C++

2006-12-21T11:47:00.001+02:00

... .However, another good reason to inline is that you can sometimes speed up your program by inlining the right function. Instead of calling the function every time it is invoked, the compiler will replace the function call with a copy of the function body.
[from the page given in the link. Also read Why not inline everything?]

And here is my project for speed comparison of inline defined function and class defined function in Visual C++:

First: Copy and paste below codes with the correct name into header files in your project.

//Filename:MyMath.h
#include
using namespace std;

class Add{
public:
int add_inline( int a,int b){
return a+b;
}
int add_class_def(int a1,int b1);
};

========================================================

// Filename:stdafx.h

// include file for standard system include files,
// or project specific include files that are used frequently, but
// are changed infrequently
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
// This source code is only intended as a supplement to the
// Microsoft Classes Reference and related electronic
// documentation provided with the library.
// See these sources for detailed information regarding the
// Microsoft C++ Libraries products.
#pragma once
#define WIN32_LEAN_AND_MEAN // Exclude rarely-used stuff from Windows headers
// turns off ATL's hiding of some common and often safely ignored warning messages
#define _ATL_ALL_WARNINGS
#ifndef _WIN32_WINNT
#define _WIN32_WINNT 0x0403
#endif
// TODO: this disables support for registering COM objects
// exported by this project since the project contains no
// COM objects or typelib. If you wish to export COM objects
// from this project, add a typelib and remove this line
#define _ATL_NO_COM_SUPPORT
#include

Second: Below codes are the cpp files for your project.

//Filename:Main.cpp
#include "MyMath.h"
#include "stdafx.h"
#include

using namespace std;
void main()
{
DWORD startTime,endTime,difTime;

int a=1;
int b=2;
int c;
Add testAdd;

// use inline function declared and defined in header file MyMath.h
startTime=GetTickCount();
for(int i=0;i<1e9;i++){>

c=testAdd.add_inline(a,b);

}

endTime=GetTickCount();

difTime=endTime-startTime; 
cout<< "it took "<<<">

//use function defined in other cpp file 

startTime=GetTickCount();

for(int i=0;i<1e9;i++){

c=testAdd.add_class_def(a,b);

}
endTime=GetTickCount();

difTime=endTime-startTime; 

cout<< "it took "<<<">

========================================================

BlogScope

2006-12-20T14:08:00.000+02:00

Bloglarda keyword araması için faydalı bir site. Eh bizde hemen denedik ve sonucu aldık. :)

Microsoft Visual C++ .NET'de "fstream" Kullanmak

2006-12-14T00:12:00.001+02:00

Boş satırları "fstream" "0" olarak okuyor ve hataya sebep oluyor.
Eğer data dosyasında bir satır sonunda "enter" a basılırsa data dosyası okurken bu kısımlar "0" okunur ve data saklanan yapıya 0 gönderilir. Bu durumdan haberdar değilseniz hatanın nerede olduğunu bulmak oldukça zorlaşır.
Debug yapıp bulurum derseniz de başınız dertte demektir.
En son debug yaparken breakpoint koyduğum yere 5 dak. 44 sn sonra gelebildi Microsoft Visual C++ .NET.
Dosyadan data okuduğunuz while loop unun içine yazılacak aşağıdaki if check i bu problemin oluşma ihtimalini ortadan kaldırır.

if(!isdigit(file_to_read.peek())) {
file_to_read.ignore();
continue;
}

sizeof an Array in C++

2006-12-06T10:16:00.001+02:00

Do not hestitate to use the below code. Just gives the size of an array in C++. :)
double array = {1.0,2.0,3.0,4.0,5.0};
int size = sizeof array / sizeof array[0];
Altough it is too long to write (just for taking the size) and hard to understand what is calculated, this code gives the result as 5.

Elementary Calculus: An Approach Using Infinitesimals

2006-12-05T23:20:00.000+02:00

Elementary Calculus
Infinitesimal elemanlar kullanarak birçok işimizde kullandığımız matematiksel denklemleri türetmeye çalışınca bu infinitesimal approach iyice önem kazanmaya başladı.
Örneğin infinitesimal bir vektör ile işlem yapıyoruz. Infinitesimal vektör nedir?
Reel midir Hyperreel midir?
Burada verdiğim linkte özellikle Vector Calculus dökümanında ilgi çekecek bilgiler var.
Bahsettiğim dökümanın 8. bölümü "Hyperreal Vectors" konusunu işliyor. Bu kelimeyi duyunca burada okumayı bırakmayın. Bu bölümde Reel Vektörler ile de ilginç teoremler var. Örneğin:
Teorem: Bir vektör reeldir ancak ve ancak vektörün boyu ve yönü reel ise.
Bu teoremden sonra da boyu reel olan ancak yönü reel olmayan bir vektöre örnek veriyor.

Yeni Eymir Maceraları

2006-12-02T14:50:00.000+02:00

Bugün Eymir'de bisiklet için tepe üzerinde güzel bir patika yol bulduk.

Constant Norm Differentiation

2006-11-14T15:10:00.001+02:00

See derivative of a vector function of a constant norm

Araba diferensiyelinin ismi nereden gelir?

2006-11-14T14:32:00.000+02:00

Diferensiyel kelimesinin arabaların güç aktarma organlarında kullanılmasının sebebi özellikle viraj dönüşlerinde motor gücünün aktarıldığı tekerleklerin farklı hızlarda dönebilmesini sağlamasıdır. Ayrıca tek tekerleğin kitlendiği durumlarda da diğer tekerleğin dönmesine izin verir.
Ama bence diferensiyel operatörünün şu özelliğinden almış olmalıydı, bu güzelliği hakediyor çünkü.
Matematikte Diferensiyel operatörünü uyguladığımız bir vektörün yönü 90 derece değişir. Bir vektörün türevi kendisine diktir.
Aşağıdaki şekilde de görüldüğü gibi motordan çıkan kırmızı şaftın yönü diferensiyele aktarıldıktan sonra 90 derece değişiyor ve sonuç olarak kendisine dik bir yöne (tekerleklere doğru) dönüyor.

First Downhill attraction

2006-09-17T16:27:00.000+03:00

The beginning of the Sunday. Most probably the first downhill rider in Ankara, as well as in Metu.

Future Technology: internally geared bicycles

2006-07-18T22:16:00.000+03:00

Mountain bike repair photos

2006-07-17T13:20:00.000+03:00

Pi formulas

2006-07-17T11:41:00.001+03:00

How to get exactly Pi by series expansion of Legendre Polynomial about functions of Sin and Cos (circular functions):
Here is the mathematica notebook...

Mountain Bike Repair

2006-07-15T19:36:00.000+03:00

Adım adım dağ bisikleti tamiratı:
1-Bir parçayı değiştirmek için gerekli argümanları iyice gözden geçirmek gerek.
Eğer aynı marka parça bulamıyorsanız çok daha dikkatli olunmalı. Hele bisikletiniz benimki gibi emektarsa. Bu arada bana Beldesan Colorado gibi bir efsaneyi taa 1992 de alan ağabeyim Bülent'e nekadar teşekkür etsem azdır. Efsane dedim, abarttığımı sanmayın. O zamanlar Beypazarı'ndaki belkide en iyi bisiklet benimkiydi, Shimano Altus C10 gibi uzun ömürlü ve muazzam hassasiyete sahip vites attırıcıları sayesinde hissettiğiniz ivme bağımlılık yapardı, yine 14 sene hiç değiştirmeden kullandığıma kimseyi inandıramadığım fern balataları ve V-freni sayesinde arka tekerleğini yarım metre havaya kaldıran "havalı çocuk" olmanızı sağladığı gibi trafikte güven verirdi vs. İşte buydu Colorado.
Geçen hafta bu efsaneyi aya kaldırmak için harekete geçtim ve bihayli uğraştıktan sonra bugün bitirdim.
Neyse, adım adım yaptığım tamiratı anlatmak istediğim için yazıyorum.
Parça değişiminden bahsediyordum.
Dikkatli olunmalı dedim çünkü muhtemelen aynı markadan bulamayacaksınız ve yeni aldığımız parçaya dizayn edilmemiş bir gövdeye, boyuna veya maşaya monte edeceksiniz (Örneğin yeni model v-vitesler eski geniş jantlara uygun olmayabilir). Önemli birşeyde ayar yapmaktan aşınmış eski vidalarınız yeni ayarlar için yorgun olacak. Yani benim asıl sözüm 10 yıldan yaşlı bisikletleri tamir edenlere olacak.
Şimdilik resimlerle idare edelim artık zamanla yazmaya devam ederiz.

Eymir maceraları

2006-07-11T11:12:00.000+03:00

Cybernetics, mathematics

2006-03-12T01:53:00.000+02:00

Cybernetics and Norbert Wiener

Jumping on the lake of ice

2006-02-25T00:56:00.000+02:00

Last summer i was able to jump only near of the lake (Eymir / Ankara).
Now on the lake...

Fundamental Theorem of Algebra

2006-02-23T19:54:00.000+02:00

Every polynomial equation having complex coefficients and degree >=1 has at least one complex root.
Again we see the importance of complex numbers.
This may be a good reason to start teaching mathematics from complex numbers.

Aerospace and Vector Calculus

2006-02-18T23:35:00.000+02:00

Vector Calculus and orthogonality are very fundemental works in aerospace field.
It is very interesting, you want to go in x direction but you are mostly dealing with the z axis (principal normal direction about x axis) to produce lift for the vehicle.
Ok i will explain what i wrote later :)

Cauchy-Schwartz inequality

2006-02-18T23:15:00.000+02:00

Cauchy-Schwarz inequality was already obvious from triangle inequality.
These mathematicians may have an influental person behind them. :)
My proof with mathematica:

The posts waiting for publishing

2006-02-18T21:28:00.000+02:00

* - Biking on the snow and ice.
* - Marketing your own product.
* - The vector definition is absent.
- There should be an extra axiom for the definition of vector space and vector.
* - Why we differentiate?

Why we use "R", "r" in vector notations

2006-02-18T21:01:00.000+02:00

In general when we want to define a vector to a point (Let's say from the origin of the coordinate system used)the letter we use to imply this vector will be "r" or "R".
It should have many reasons, but i think some of them are like this:
1 - It defines the "R"elation between two points. (The origin and the point defined)
2 - It implies the "R"esultant vector.

I will look for others...
If you have any idea please write.

test for statcounter

2006-01-29T17:33:00.000+02:00

View My Stats

How to share a USB device within two computers

2006-01-29T00:22:00.000+02:00