Great video from christmas lectures of 1991 by Dr. Richard Dawkins.
I was feeling a bit blue yesterday and tried to find purpose in life [I have long outgrown religions] and hit upon this video. I was totally refreshed by this video. Although I have seen it earlier, every time I see it, I get a different perspective. His style of explanation is excellent.
Monday, January 24, 2011
Nice putnam question
Prove that this is not prime for any n.I found this question in putnam question paper and it has real elegant solution too.
It is too good to not to solve it yourself.
Sunday, January 16, 2011
How to setup own SVN server in 5 minutes on Mac OS X
1. Install Macports
2. Install subversion
sudo port install subversion
3. Start svn server
svnserve -d --listen-port 4000 -r /repository -T
4. Create repository
svnadmin create /repository/testPrograms
5. Configure repository
Edit /repository/testPrograms/conf/svnserve.conf
and uncomment
auth-access = write
password-db = passwd
Edit /repository/testPrograms/conf/passwd
and add users
[users]
Fakrudeen Ali Ahmed = mypassword
Now svn server is ready to serve the repository.
Create a client folder
and do
svn co svn://localhost:4000/testPrograms
and we are ready to use our repository!
2. Install subversion
sudo port install subversion
3. Start svn server
svnserve -d --listen-port 4000 -r /repository -T
4. Create repository
svnadmin create /repository/testPrograms
5. Configure repository
Edit /repository/testPrograms/conf/svnserve.conf
and uncomment
auth-access = write
password-db = passwd
Edit /repository/testPrograms/conf/passwd
and add users
[users]
Fakrudeen Ali Ahmed = mypassword
Now svn server is ready to serve the repository.
Create a client folder
and do
svn co svn://localhost:4000/testPrograms
and we are ready to use our repository!
Top Must have developer tools
It is a mix of Top tools and some tools won't apply to some developers.
1. IntelliJ IDEA - Best IDE in the world for JAVA. Or Resharper for C# developers.
2. Textpad - Best text editor
3. Beyond Compare - Best diff tool
4. MIT-Scheme - Rapid proto typing of simple algorthms or rapid calculation of familiar functions like n!
5. SVN - Our own version repository for versioning local test programs, docs and so on.
1. IntelliJ IDEA - Best IDE in the world for JAVA. Or Resharper for C# developers.
2. Textpad - Best text editor
3. Beyond Compare - Best diff tool
4. MIT-Scheme - Rapid proto typing of simple algorthms or rapid calculation of familiar functions like n!
5. SVN - Our own version repository for versioning local test programs, docs and so on.
Tuesday, January 11, 2011
How to become good theoretical physicist
How to become good theoretical physicist.
't hooft is a Nobel laureate who worked in both general relativity and quantum field theory and great teacher.
http://www.phys.uu.nl/~thooft/theorist.html
't hooft is a Nobel laureate who worked in both general relativity and quantum field theory and great teacher.
http://www.phys.uu.nl/~thooft/theorist.html
Saturday, January 8, 2011
Greatest mathematicians ever!
I got a question today in aardvark - who are greatest 20th century mathematicians?
I answered Turing, Godel and Von Neumann.
Then I searched in google about who are greatest mathematicians. I saw many lists and I decided to create my own list based on my own knowledge - of course it need not be objective as it is my own list!
My criteria are a bit harsh - If two people invented the same thing, the person who invented it first or Who is more influential in other respects are given the credit. One good example is evolution. We always credit it to Darwin although Wallace came up with the idea around the same time. So credit for calculus goes to Newton not his opponent. Also I give more credit for a great foundational discovery than breadth of output - Best example is Euler for the latter - but Godel beats him with his incompleteness theorem.
1. Sir Isaac Newton
Greatest by a long distance to me. His invention of Calculus alone would have placed him here. But he discovered binomial theorem, Newton's method for square roots etc.
2. Carl Frederich Gauss
Greatest pure mathematician [or at least one mainly known for mathematics]. He discovered many things like Non Euclidean geometry, Gaussian curvature etc.
3. Kurt Godel
He found incompleteness theorem, which shattered the hope for a theorem proving machine which will find all theorems.
4. Archimedes
From his writings I can see he almost invented integral calculus. Particularly have a look at things like his approximation for PI.
5. Riemann
Invented things which were precursor to General Relativity [Riemann curvature] and a rigorous definition for Integral calculus and contributed to the theory of prime numbers [Riemann zeta function]
6. George Cantor
He proved real numbers aren't countable - so vastly bigger than natural numbers using his famous diagonal slash argument.
7. Alan Turing
He discovered the theory of computability with his Turing machines. It provided the formal basis for computers and proved there are things in Mathematics which are un computable.
8. Euclid
I think he is more of a chronicler than discoverer. But since I don't know who actually discovered his results I might as well give him the credit. Of course he gets into the list due to Elements.
9. Euler
I have to include Euler for the sheer amount of his work. On complex numbers like Euler's formula or his discovery of the sum of 1/1^2+1/2^2 etc. Although in my personal opinion none of them are as path breaking as others in the list.
10. Dedekind
I am including Dedekind for his rigorous definition of real numbers [which are anything but real!] - Although we should probably mention people like Cauchy and Weirstrass, I still think single most important was that of Dedekind.
I answered Turing, Godel and Von Neumann.
Then I searched in google about who are greatest mathematicians. I saw many lists and I decided to create my own list based on my own knowledge - of course it need not be objective as it is my own list!
My criteria are a bit harsh - If two people invented the same thing, the person who invented it first or Who is more influential in other respects are given the credit. One good example is evolution. We always credit it to Darwin although Wallace came up with the idea around the same time. So credit for calculus goes to Newton not his opponent. Also I give more credit for a great foundational discovery than breadth of output - Best example is Euler for the latter - but Godel beats him with his incompleteness theorem.
1. Sir Isaac Newton
Greatest by a long distance to me. His invention of Calculus alone would have placed him here. But he discovered binomial theorem, Newton's method for square roots etc.
2. Carl Frederich Gauss
Greatest pure mathematician [or at least one mainly known for mathematics]. He discovered many things like Non Euclidean geometry, Gaussian curvature etc.
3. Kurt Godel
He found incompleteness theorem, which shattered the hope for a theorem proving machine which will find all theorems.
4. Archimedes
From his writings I can see he almost invented integral calculus. Particularly have a look at things like his approximation for PI.
5. Riemann
Invented things which were precursor to General Relativity [Riemann curvature] and a rigorous definition for Integral calculus and contributed to the theory of prime numbers [Riemann zeta function]
6. George Cantor
He proved real numbers aren't countable - so vastly bigger than natural numbers using his famous diagonal slash argument.
7. Alan Turing
He discovered the theory of computability with his Turing machines. It provided the formal basis for computers and proved there are things in Mathematics which are un computable.
8. Euclid
I think he is more of a chronicler than discoverer. But since I don't know who actually discovered his results I might as well give him the credit. Of course he gets into the list due to Elements.
9. Euler
I have to include Euler for the sheer amount of his work. On complex numbers like Euler's formula or his discovery of the sum of 1/1^2+1/2^2 etc. Although in my personal opinion none of them are as path breaking as others in the list.
10. Dedekind
I am including Dedekind for his rigorous definition of real numbers [which are anything but real!] - Although we should probably mention people like Cauchy and Weirstrass, I still think single most important was that of Dedekind.
Friday, January 7, 2011
How the distance from stars are measured
We all know it is using parallax. But I didn't understand how we can actually measure the parallax angle. Finally this link explained it well. It is because we know the angle subtended by telescope's field of view.
If whole picture is 10 degrees and picture width is 10 centimeter and star seems to move 1 centimeter its angle is 1 degree. of course at 1 degree we will be fried to death - but that was just an example!
If whole picture is 10 degrees and picture width is 10 centimeter and star seems to move 1 centimeter its angle is 1 degree. of course at 1 degree we will be fried to death - but that was just an example!
Why we are evolved animals
I was thinking about similarities and differences between animals [minus humans of course] and us.
If God wanted us to be different from Animals he could have done so many different things. Why should he so confuse us faithfuls by implying with so many "signs of the devil".
1. Base our genetic code on something other than DNA. Even retro viruses are better than us in this respect - they use RNA. Replacing the carbon in nuclic acid with say silicon, because we are special.
2. Why are we based on same cells as other animals - or based on cells at all. We could have used some other mechanism which would have removed cancer from us forever as well. Surely a benevolent [particularly to people, given that we are special] God should have gone with this.
3. Why do we have the same micro organism [mito chondria] for oxidation processes. Atleast if we are diffrent we could have had different mito chondria with different DNA.
4. Why our embryos look so similar to other animals, even to fish. Even we have a tail as embryo, which is so lowly considering exalted state of human beings.
5. Even obvious external apperance, why do we have same four limbs and two eyes and two ears as all other mammals. In this sense, Dolphins and Whales are more special than us. I seriously think they are the ones especially chosen by God. Devil is just misleading us to think that it is we who are special, particularly with the help of some human beings who claim to be prophets etc. We should better beware of God's wrath. What if these guys claiming to be prophets are lying? I have never known them personally anyway. Particularly some prophets morals look much worse than me, a known sinner! Atleast I wouldn't want to marry a 6 year old or ask people to hate their parents for me.
Google sets
I wanted to find website creation softwares similar to wordpress and I used
Google sets to generalise wordpress and joomla and it quickly turned up mambo and drupal.
It is pretty useful. I played with it and it generalised Tendulkar and Kallis to Lara, Murali etc.
But it didn't work for Karunanidhi and Jayalalitha!
Google sets to generalise wordpress and joomla and it quickly turned up mambo and drupal.
It is pretty useful. I played with it and it generalised Tendulkar and Kallis to Lara, Murali etc.
But it didn't work for Karunanidhi and Jayalalitha!
Xserver unable to start after reboot
Suddenly my xserver stopped working after reboot.
I wasted almost a day trying to start xserver again. Then I went through some sites and finally I found a work around. I simply linked usr/X11R6/lib/libXfont.so.1 to libXfont.so.1.4.1 through the intermediary of libXfont.so.1.5 symbolic link and it started working.
ls -la /usr/X11R6/lib/libXfont.so*
lrwxrwxrwx 1 root root 15 Jan 3 11:16 /usr/X11R6/lib/libXfont.so.1 -> libXfont.so.1.5
lrwxrwxrwx 1 root root 22 Jul 16 17:49 /usr/X11R6/lib/libXfont.so.1.4.1 -> /usr/lib/libXfont.so.1
lrwxrwxrwx 1 root root 32 Jul 16 18:33 /usr/X11R6/lib/libXfont.so.1.5 -> /usr/X11R6/lib/libXfont.so.1.4.1
-rwxr-xr-x 1 root root 388012 Jul 26 2008 /usr/X11R6/lib/libXfont.so.1.5.bak
I wasted almost a day trying to start xserver again. Then I went through some sites and finally I found a work around. I simply linked usr/X11R6/lib/libXfont.so.1 to libXfont.so.1.4.1 through the intermediary of libXfont.so.1.5 symbolic link and it started working.
ls -la /usr/X11R6/lib/libXfont.so*
lrwxrwxrwx 1 root root 15 Jan 3 11:16 /usr/X11R6/lib/libXfont.so.1 -> libXfont.so.1.5
lrwxrwxrwx 1 root root 22 Jul 16 17:49 /usr/X11R6/lib/libXfont.so.1.4.1 -> /usr/lib/libXfont.so.1
lrwxrwxrwx 1 root root 32 Jul 16 18:33 /usr/X11R6/lib/libXfont.so.1.5 -> /usr/X11R6/lib/libXfont.so.1.4.1
-rwxr-xr-x 1 root root 388012 Jul 26 2008 /usr/X11R6/lib/libXfont.so.1.5.bak
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