Hello World – Erlang

The easiest way to install Erlang on MacOS is by downloading the .dmg of Erlang here. And then you will get Erlang installed.

And here’s the example of Hello World using Erlang.

Useful Links:

1. http://digitalsanctum.com/2009/10/01/installing-erlang-on-mac-os-x/
   
2. http://www.erlang.org/download.html
3. http://www.waratuman.com/2010/01/12/installing-erlang-on-mac-os-x/
4. http://www.claystuart.com/
5. http://www.erlang.org/documentation/doc-5.1/doc/getting_started/getting_started.html
6. http://www.trapexit.org/Running_Erlang_Code_From_The_Command_Line

Polynomial Basis Squaring

Finally have successfully found some spare time to do coding to solve this polynomial squaring:

And this is the result, x^5 + x + 1 :

Why Python?

Our research group is developing a library for finite field operations on very long bits, so we start gathering information about the performance of Python on scientific programming, big numbers especially for cryptography.
Here are some important links related to Python for scientific and cryptography implementation:

1. http://www.tutorialspoint.com/python/python_numbers.htm – about Python number representations
2. https://pypi.python.org/pypi/PyECC – a module for implementing Elliptic Curve Cryptography
3. http://theunixgeek.blogspot.com/2008/09/c-vs-python-speed.html – Python compared to C
4. http://www.linuxjournal.com/magazine/use-python-scientific-computing – the use of Python for scientific computing
5. http://scipy-lectures.github.com/ – Python Scientific Lecture Notes
6. http://www.scientificpython.net/ – Scientific Computing with Python
7. http://wiki.python.org/moin/NumericAndScientific – list of modules and tools for various implementation in Python
8. http://ubuntuforums.org/showthread.php?t=1581805 – Python power for large numbers
9. http://programmers.stackexchange.com/questions/128589/how-to-handle-large-numbers – handling big numbers with Python
10. http://www.daniweb.com/software-development/python/threads/364584/very-large-numbers – library for big numbers in Python
11. http://www.daniweb.com/software-development/python/threads/364584/very-large-numbers – Python can handle very big numbers
12. http://code.google.com/p/ecc4pys60/wiki/Roadmap – Elliptic Curve Cryptography implementation on S60 using Python
13. https://gist.github.com/bellbind/1414867 – Elliptic Curve Cryptography implementation in Python

Python: Converting String to Binary

A simple code on how to convert string to binary, accessing array string and performing shift operation on binary

#!/usr/bin/python

a_str = ’10110011′
b_str = “00101010″
a_bin = int(a_str, 2)
b_bin = int(b_str, 2)

print “a “, int(a_bin), a_str
print “b “, int(b_bin), b_str
print “a[0] “, a_str[0]
print “b[0:3]“, b_str[0:3]

#print “c “, c, bin(c)[2:]

print “a << 2 “, a_bin << 2, bin(a_bin << 2)[2:]
print “b >> 2 “, b_bin >> 2, bin(b_bin >> 2)[2:]

The result:

Python: Bit Operations

Basic bit operations in Python:

#!/usr/bin/python 

a = 60            # 60 = 0011 1100 
b = 13            # 13 = 0000 1101 
c = 0

print "a = ", (bin(a)[2:]);
print "b = ", (bin(b)[2:]);

c = a & b;        # 12 = 0000 1100
print "a & b = ", (bin(c)[2:]);

c = a | b;        # 61 = 0011 1101 
print "a | b = ", (bin(c)[2:]);

c = a ^ b;        # 49 = 0011 0001
print "a ^ b = ", (bin(c)[2:]);

c = ~a;           # -61 = 1100 0011
print "~a = ", (bin(c)[2:]);

c = a << 2;       # 240 = 1111 0000
print "a <> 2;       # 15 = 0000 1111
print "a >> 2 = ", (bin(c)[2:]);

Result:

An interesting link about bit operation algorithm implementation in Python is here.

Crypto vs Code

Cryptography is the study of mathematical techniques related to aspects of information security such as confidentiality, data integrity, entity authentication, and data origin authentication. [Handbook of Applied Cryptography - Alfred J. Menezes Paul C. van Oorschot Scott A. Vanstone]

Coding is needed for efficient reliable digital transmission and storage. [Error Control Coding - Shu Lin, Daniel J. Costello]. Coding theory is is the study of the properties of codes and their fitness for a specific application. Codes are used for data compression, cryptography, error-correction and more recently also for network coding. Codes are studied by various scientific disciplines—such as information theory, electrical engineering, mathematics, and computer science—for the purpose of designing efficient and reliable data transmission methods. This typically involves the removal of redundancy and the correction (or detection) of errors in the transmitted data. [Wikipedia]

2012 in review

The WordPress.com stats helper monkeys prepared a 2012 annual report for this blog.

Here’s an excerpt:

4,329 films were submitted to the 2012 Cannes Film Festival. This blog had 18,000 views in 2012. If each view were a film, this blog would power 4 Film Festivals

Click here to see the complete report.

Resolving Java Heap Space Error

My previous code processed two tables with thousands of rows and had problem with Java Heap Space like shown below:

 

 

To overcome this out of memory problem, we should increase the heap size by typing this on command prompt:

 

And now it works:

 

More useful links about Java heap space:

1. http://javarevisited.blogspot.com/2011/09/javalangoutofmemoryerror-permgen-space.html
2. http://javarevisited.blogspot.com/2011/05/java-heap-space-memory-size-jvm.html
3. http://stackoverflow.com/questions/1565388/increase-heap-size-in-java
4. http://javahowto.blogspot.com/2006/06/6-common-errors-in-setting-java-heap.html
5. http://viralpatel.net/blogs/jvm-java-increase-heap-size-setting-heap-size-jvm-heap/
6. http://www.devx.com/tips/Tip/5578
7. http://publib.boulder.ibm.com/infocenter/wmbhelp/v6r1m0/index.jsp?topic=%2Fcom.ibm.etools.mft.doc%2Fac55070_.htm
8. http://www.ehow.com/how_5347474_set-java-heap-space.html

Hello World – Python

I’m learning Python

This is the version of Python I’m using:

And then start using vi to type the code:

The listing of the code:

And run the code:

Ok that’s it for now, I don’t know yet what is so good about Python compared to other languages I’m familiar with (C/C++, Java, Perl). Will post more about this as soon as I learn more about Python.

Inserting into MySQL Table

Here’s how to get result from a table using ResultSet and use it as variables to be inserted to another table using PreparedStatement

import java.sql.*;
import java.sql.DriverManager;
import java.sql.Connection;
import com.mysql.jdbc.Driver;
import java.net.*;
import java.io.*;
public class CountUser{
public static void main(String args[]) {
try{
Class.forName("com.mysql.jdbc.Driver");
// Connection connection = DriverManager.getConnection("jdbc:mysql://167.205.24.50/table","root","");
Connection connection = DriverManager.getConnection("jdbc:mysql://localhost/table","root","");
Statement st1 = connection.createStatement();
Statement st2 = connection.createStatement();

ResultSet rs1 = st1.executeQuery("SELECT * FROM user");

while (rs1.next()) {
java.sql.Date date = rs1.getDate(5);
String strDate = date.toString();

PreparedStatement ps = connection.prepareStatement("INSERT INTO count_temp (no, date) VALUES (?,?)");
ps.setInt(1, i);
ps.setString(2, strDate);
ps.executeUpdate();
}
}
catch (Exception e){
System.out.println("Error: " + e);
}
}
}