Wednesday, April 13, 2011


Favorite presentations from Prezi:

Monday, April 11, 2011


Sunday, April 10, 2011


A new dialect of Lisp

"Arc is designed for exploratory programming: the kind where you decide what to write by writing it. A good medium for exploratory programming is one that makes programs brief and malleable, so that's what we've aimed for. This is a medium for sketching software.Arc is unfinished. It's missing things you'd need to solve some types of problems. But it works well for basic web apps.

The first priority right now is the core language. We're trying to continue McCarthy's axiomatic approach all the way up to a complete language for day to day programming."

Thursday, April 7, 2011

Performance of comparing arrays

For the test I have used 2.3 mb file, being read to a byte array before all tests, and each test is run 100 times.

Release, ms

Debug, ms

MemCmp and UnsafeBytesCompare8Step are the fastest
UnsafeBytesCompareMs is used in .NET to compare Strings.

Performance of MemCmpFromPtr is as much as the MemCmp performance if initializing of IntPtr
is implemented outside the function.

MemCmp uses memcmp

Source code:

Tuesday, April 5, 2011

Python resource and extensions




1. C-Extension for Python:

Cython is a language that makes writing C extensions for the Python language as easy as Python itself. Cython is based on the well-known Pyrex, but supports more cutting edge functionality and optimizations.
The Cython language is very close to the Python language, but Cython additionally supports calling C functions and declaring C types on variables and class attributes. This allows the compiler to generate very efficient C code from Cython code.
This makes Cython the ideal language for wrapping external C libraries, and for fast C modules that speed up the execution of Python code.

2. Mathematics open source library:
5. SciPy
6. PyCuda:
7. Mrjob:
    Run Hadoop Streaming jobs on Amazon Elastic MapReduce or your own Hadoop cluster
8. CRC:
     An event-driven networking engine written in Python
10. Requests:
11. MatplotLib:
12. Py-LLVM:
13. Kalman filtering:
14. OpenGL:
15. MapReduce on Python:
16.  Natural language toolkit
17. Astronomy

Open Source Python Tools for Classification (

  • Monte - less comprehensive than Orange, written purely in Python (i.e. noSWIGed C++). Looks interesting (has several classifiers algorithms), but the APIs seems to be in an early phase (relatively new tool in version 0.1.0)
  • libsvm - Python API for most popular open source implementation of SVM.Note: libsvm is also included with Orange and PyML. (I used this tools during my PhD a few years ago)
  • RPy - not exactly a classification tool, but it is quite useful with a statistics tool when you are doing classification (it has a nice plotting capability, not unlike matlabs), check out the demo.
  • PyML - also less comprehensive than Orange (specialized towards classification and regression, it supports SVM/SMO, ANN and Ridge Regression), but it has a nice API. Example of use: 
    from PyML import multi, svm, datafunc
    # read training data, last column has the class
    mydataset = datafunc.SparseDataSet('', labelsColumn = -1)
    myclassifier = multi.OneAgainstRest(svm.SVM())
    print "cross-validation results",
My recommendation is to either go with Orange or with PyML.


Harshad numbers

Inverse Symbolic Calculator
P.S. Infinity

Online encyclopedia of integer sequences

1. A019460: 2, 3, 3, 5, 10, 13, 39, 43, 172, …
2. A006567: 13, 17, 31, 37, 71, 73, 79, 97, 107, …
3. A001462: 1, 2, 2, 3, 3, 4, 4, 4, 5, 5, 5, 6, 6, 6, 6, …
4. A005228: 1, 3, 7, 12, 18, 26, 35, 45, 56, 69, …
5. A006751: 2, 12, 1112, 3112, 132112, 1113122112, …
6. A004000: 1, 2, 4, 8, 16, 77, 145, 668, ...
7. A007449: 7, 9, 40, 74, 1526, 5436, 2323240, 29548570, …
8. A006933: 2, 4, 6, 30, 32, 34, 36, 40, 42, 44, 46, 50, …

Tiny OS

TinyOS is an open source, BSD-licensed operating system designed for low-power wireless devices, such as those used in sensor networks, ubiquitious computing, personal area networks, smart buildings, and smart meters

To be continued....

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