Google, Asian telecoms to build $300 mln undersea cable to Japan

Interesting: Google has come to an agreement with five Asian telecom operators to deploy an undersea cable between the US and Asia.

NASA Space Sounds

The space is never truly empty - photons created in stars and in all particules interactions are all over the place, resulting in electromagnetic waves that can be recorded and converted to sound. 

NASA probes recorded these electromagnetic waves and converted them to sounds that can be played. Here are a few samples. 

P.F. Chang's Provides Data Breach Update, Confirms Compromised Locations

The Chinese restaurant chain has released the list of its compromised locations: here.

Happy Birthday Fortran (II)

In the previous article, I show a small piece of code. Let's have a look at a larger one.

In the sixties, Edward Lorenz, who was working at MIT, found that a weather model he built exhibited a very strange behavior: two sets of inputs, only different by minute quantities, would initially behave similarly and then diverge widely.

After he studied the phenomenon, he showed an example of another system that had the same property, a system which is known as Lorenz's attractor. Several texts have been published on the subject, let's just recap the main points:

• The system oscillates between two points (attractors)
• Two different starting points will lead to two different trajectories
• A trajectory never repeats itself

As a computer represents real numbers with a finite precision, the second point is open to discussion: if two trajectories are so close that the difference between the closest points of each is below the machine precision, the rounding may result in the one of the trajectories being altered. This is actually what happens and started Lorenz investigations: while the internal representation of the numbers was up to 6 decimals, Lorenz's printout was only 4. When he stopped his experiment and restarted it later from an earlier point, the results started by being the same, then diverged. The field of chaos theory was created ...

My second homage to Fortran is a program that generates the coordinates for the points of the Lorenz's attractor. The code can be found in my GitHub repository.

Two methods are used to calculate the points: Explicit Euler (or Forward Euler), Implicit Euler (or Backward Euler) and a mixed method, which uses the average of a backward and forward Euler step.

The Explicit Euler is quite simple and straightforward to implement: the three differential equations are explicit and do not require solving anything special.

The Implicit Euler, on the other hand and by extension the Implicit-Explicit Euler, is a bit more challenging: each step requires solving a system of three equations with three unknowns. This is done - in my case - using Newton's method, which in turn requires computing the inverse of the Jacobian matrix, which is performed in my code using Gauss-Jordan decomposition: starting with the original matrix and the identity matrix, I apply all the operations needed to transform the original matrix into the identity matrix. As the same operations are applied to the second (starting as the identity) matrix, the result is that the original matrix is transform into the identity matrix, and the identity matrix is transformed into the inverse of the original matrix.

Both the Implicit and Explicit Euler are first order methods, the mixed Implicit-Explicit Euler is a second  order method: its convergence is faster and it is more stable. (Read here for a discussion of the Backward and Forward Euler methods)

IP Informer - a program to look for several IPs in several black lists

So, you have a list of IP addresses you would like to quickly check against several black lists such as Abuse.ch 's Zeus Tracker, Spy Eye Tracker, Palevo Tracker, Feodo Tracker or the Malware Domain List. Here is a small tool in Google's go language that does exactly that: it takes a file containing a list of IP addresses (one per line) and checks each of them into these lists. Given that the black lists are defined in a configuration file, it is very easy to add or remove specific lists.

I keep adding new features, so feel free to check the GitHub repository from time to time.

Happy Birthday Fortran!

For some of us, the name "Fortran" or "FORTRAN" evokes a computer language closely associated with massive super computers and complex mathematical models. For others, it is reminiscent of a war with C++ for the supremacy in the scientific computing world.

It has been continuously developed since its initial publication in 1957, and the latest revision came out in 2010, with another minor revision planned for 2015. Fortran is not dead, far from that, even if it has a though competition from other languages such as Haskell, Clojure or even Python.

Wikipedia has an extensive history of the language.

The first example of code in Fortran I will present is the determination of the fraction that generates a given pattern.

Let's take 0.1278, where the underlined part repeats ad infinitum. The fraction needed to obtain this value is 211/1650. For the rest of this post, I will call the part that repeats the repeated part and the part that does not repeat the prefix. The algorithm to find the fraction is well known, let's focus on the code.

It contains three parts: computing the non reduced fraction, computing the greatest common denominator (gcd) of the numerator and denominator and reducing the fraction to a numerator and a denominator that are relatively prime. Let's start with the gcd.

For this, I use Euclid's algorithm. The code in Fortran 95 to achieve this is

function gcd(a, b) result(c)
! Returns the GCD of a and b
 integer :: a,b,c,u,l,m
 if ( a > b ) then
   u = a
   l = b
 else
   u = b
   l = a
 end if
 do while (l > 0)
    m = modulo(u,l)
    u=l
    l=m
 end do
 c=u
 return
end function

It consists of a few parts: having u contains the largest value, l the smallest then looping until u modulo l  is 0. The simplification subroutine is even simpler.

subroutine simplify(a, b, c, d)
! Returns the fraction a/b in its simplified form
! c/d where c and d are relatively prime
 integer, intent(in) :: a,b
 integer, intent(out) :: c,d
 integer :: n,gcd
 n=gcd(a,b)
 c=a/n
 d=b/n
 return
end subroutine


Now, the core of the problem is solved by two other functions - one that takes care of fractions with a prefix, the other one of fractions without a prefix. There are some issues in the code presented, but at this point and for a simple presentation, this is not important.

subroutine findfractionpref(pref, rept, mpref, a, b)
! Returns the fraction a/b such as its division gives the pattern prefreptreptrept ! ....
! With the necessary multiplier
 integer, intent(in) :: pref, rept, mpref
 integer, intent(out) :: a, b
 integer :: d1, d2, num, den
 d1=1+floor(log10(real(pref)))
 d2=1+floor(log10(real(rept)))
 num=((pref*10**(d2)+rept)-pref)
 den=10**(d1+d2)-10**(d1)
 if ( mpref > 0) then
  den=den*10**mpref
 else
  num=num*10**mpref
 end if
 call simplify(num, den,a , b)
 return
end subroutine

subroutine findfractionnopref(rept, a,b)
! Returns the fraction a/b such as its division gives the pattern reptreptrept...
 integer, intent(in) :: rept
 integer, intent(out) :: a,b
 integer :: d1, num, den
 d1=1+floor(log10(real(rept)))
 num=rept
 den=10**d1-1
 call simplify(num,den,a,b)
 return
end subroutine 

Lastly, the main part of the program, used to read the various information and call the necessary subroutines.

program fractionfinder
 implicit none
 integer :: pref,rept,a,b
 character :: c
 do
  print *, 'Does your fraction include a prefix (yY/nN) or Q to quit (qQ)?'
  read(*,'(A1)'), c
  if ((c == 'y').or.(c == 'Y')) then
   print *, 'Prefix part?'
   read(*, '(I12)'), pref
   print *, 'Repeated part?'
   read(*,'(I12)'), rept
   call findfractionpref(pref,rept,0, a,b)
   print *, 'The requested fraction is ', a, '/', b
  else if ((c == 'n').or.(c == 'N')) then
   print *, 'Repeated part?'
   read(*, '(I8)'), rept
   call findfractionnopref(rept,a,b)
   print *, 'The requested fraction is ', a, '/', b
  else if ((c == 'q').or.(c == 'Q')) then
   goto 100
  end if
 end do
100 print *, 'Bye bye!'
 stop
end program



Many thanks go to Rae Simpson for the help she provided with some of the terms in this post!

New gTLD Applications

Do you know what "cruise", "pamperedchef", "通用电气公司" and "click" have in common? They are proposals for new generic top-level domain ("gTLD") names. We all know the "com", "org","uk", "be" and other "net" names such as google.com or wikipedia.org, but some companies and entities fell a bit constrained by having to use overly generic categorizations in either commercial, organizational, governmental or generic entities.

A first wave of requests created some domain specifics TLD, such as .aero, .biz, and so forth. Mikko Hypponen, the charismatic CRO of the Finnish security company F-Secure, recently posted on twitter a few examples of the next wave. He also posted the wiki page that includes all the new gTLD applications.

Surprisingly enough, there is no ".omg", ".lolcat" or ".canIhazchezburger". It is also interesting to see that the internationalized domain names are making an appearance in the TLDs.