C some Speed !!

Most programmers know that c programs are the next best thing to assembly language programs in terms of Speed , and here is yet another example .

When solving one of the problems at projecteuler.net.I Suddenly came upon the idea to compare the speed of execution of the same algorithm in different languages.

So here is the program in Three Programming languages , C , Java and Python

First in C

#include<stdio.h>
long long  LargestPrimeFactor(long long number) {
		long long n = number , i , Largestfactor = 1;
		for (i = 2; i <= (n / i); i++) {
			while (n % i == 0) {
				Largestfactor = i > Largestfactor? i : Largestfactor;
				n /= i;
			}
		}
		Largestfactor = n > Largestfactor ? n : Largestfactor;

		return Largestfactor;
	}
int main (){
	printf(" %d \n",LargestPrimeFactor(600851475143));
}

Then in Java

class ex3{
	public static long LargestPrimeFactor(long number) {
		long n = number, factor = 1 , i;
		for (i = 2; i <= n / i; i++) {
			while (n % i == 0) {
				factor = i>factor?i:factor;
				n /= i;
			}
		}
		factor = n>factor?n:factor;
		return factor;
	}
	public static void main(String [] args){
		System.out.println(LargestPrimeFactor(600851475143L));
	}
}

and now in Python

def LargestPrimeFactor(num):
        n=num
        factor = 1
        i=2
        while( i<= (n/i) ):
                while( n%i == 0 ):
                        if i>factor :
                                factor = i
                        n /= i
                i += 1
        if n > factor:
                factor = n
        return factor

print LargestPrimeFactor(600851475143)

I computed the times using the time utility in linux .

I expected the c program to win there was no doubt about that , and java was expected to come in second with python last .

$ time ./a.out
 6857

real	0m0.003s
user	0m0.004s
sys	0m0.000s

$ time java ex3
6857

real	0m0.114s
user	0m0.084s
sys	0m0.028s
$ time python ex3.py
6857

real	0m0.035s
user	0m0.028s
sys	0m0.004s

From the results its quite visible that c had won over python and python had won over java ,even though java was supposed to be faster than python.

The reason for python winning is that the cost of starting up the JVM is quite high, when compared with the cost of starting the python interpreter.

So lesson learnt If your program is short run it in python when given a choice , but still C is the king of Speed

Ps: This Question on stackoveflow goes over some more details .

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Things to do after installing Python ~ on the Fly tutorial

After installing Python on windows you may be wondering what to do next .

Well the first thing you should do is find a way to edit .py souce code files , you can use notepad or wordpad already present in windows , but i highly recommend Notepad++ because it offers some very good features like Syntax highlight and also has a vast library of Auto Completion prompts for Python , and you can also add your own .

The next thing that is to be done is Read the documentation , You can do that here: http://www.python.org/doc/ or it is found in the Python install folder under Doc.


Python ~ On the fly tutorials

I just returned from Day 1 of  a workshop on Python programming workshop @ REC .

So I have decided to get things going by writing tutorials as I learn the language , so the next post would be on installing python on windows environment .

But before we go into that lets start with what Python is , So Python is an interpreted, general-purpose high-level programming language , That was from Wikipedia , I will explain briefly but for detailed explanation refer Wikipedia,

Interpreted : Its a type of programming language that is not compiled or linked ,Normally languages like c/c++ need to be compiled into machine language and linked with the necessary modules but languages like Python which are interpreted are executed directly from the source code . Another famous example of an interpreted Language is Javascript but remember Javascript is not a programming language its a scripting language , But Python is a programming Language.

High-Level Language : A high level language is nothing but a fancy term for a programming language where you don’t really have to bother about doing dirty work of garbage collection , memory allocation and other boring stuff like that , you can just focus on coding your program , and all this mundane repetitive activities are taken care of by the Compiler  , in the case  Python it would be done by the Interpreter .

Python is really easy to pick up if you have a good foundation in programming , if not you can still start with Python .

Somehow I have a small prejudice towards block typed and strongly typed languages ,  Languages like C/C++  , I still like Python though , but I absolutely hate Basic especially Visual Basic ,thats why I always use C# instead of VB .