What a programmer needs to know about ordinary differential equations

[What are ordinary differential equations? Read my detailed notes here on Evernote:Math:ODE]

Solving an ordinary differential equation is computationally expensive. One of the most common approximation methods used to solve this is euler. Understanding this for non math buffs means a lot of effort.(Lets say "Ordinary.Differential.Equations_Tenenbaum_Pollard" has too many pages). So I wrote a python program that implements both euler and its more accurate form the predictor corrector method and thought I will share it.

What are we trying to achieve?

1. Implement euler and corrector predictor method
2. Plot them on a graph to understand their nature
3. Compare the graph plots to visually understand the accuracy differences

What equation are we trying to solve?

dy/dx = x + 2y

What python libraries do we need?

#http://matplotlib.sourceforge.net/

import math

from pylab import *

Show me the code?

http://dl.dropbox.com/u/46029347/ode.py

What are the results?

We can visually see from the following plots that

1. Reducing step size increases accuracy
2. The predictor corrector (shown with '+' ) is more closer to original equation (shown with '.' ) than the traditional euler method (shown with '*')

When we plot from 0 to 3 with step size 0.2

When we plot from 0 to 3 with step size 0.1

When we plot from 0 to 3 with step size 0.01

-- Python
-- Pure awesomeness :)

How to effectively recognize SCAMs & SPAMS

With lot of spams and scams lurking around and the con artists getting better and better all the time I thought I would compile up my set of warning signals. Feel free to comment anything I miss out.

• You are offered prize for a contest you never participated.
• You are picked in a lucky draw, and to claim the reward you have to pay some money. (You ll surely lose every penny you pay)
• You are asked to pay for a chance to participate in a bid that might get you something at an unbelievably low price. (Its like lottery right? I may win or not, but then again how do you know that dealcent.com actually picks a winner?)
• The website offers free membership, but to activate your account you need to fill out your credit card details. (Don't blame your insurance company that they 'll not settle your claims for some crap purchased of your card in Nigeria by a con man)
• You are asked to participate in a marketing scheme, your earnings depending on number of people you join for the scheme. Warning sign: there is no real product associated in the scheme/the product associated with scheme doesn't have the profit margin equivalent to the membership fees applicable
• You are asked to deposit money in an account via unsecure means (eg:direct bank transfer to account) before delivery of material
• You are asked to deposit money in an account via unsecure means (eg:direct bank transfer to account) for delivery of a material illegal in your country
• Overseas travel at your own expenses required to claim the prize
• The email claims to be from ebay/amazon/your bank but the return address is from a free account from yahoo/gmail than the from the original domain
• You do not know the sender or have any association with the organisation the sender claims to be
• The sender is listed in http://www.consumerfraudreporting.org/
• You are redirected to a login page that looks like your bank/email login page but the url is from some other domain
• The website of the offer has millions of testimonials and statistics, but it is never mentioned in your circle of friends nor on any other public forum online
• You are the 1000000th visitor of the site
• The product claims to provide benefits only after a prolonged duration (few months to years) and is not certified by any credible agency
• Shortened url depicting porn or sensationalized news posted in social networks
• Websites requiring to enter username and password of other unrelated companies eg: google/yahoo/fb  (these use open id so you shouldn't be entering your credentials anywhere else)
• You are one among 100s of email ids in the to field and there is no one group that relates you to them.

Let me know your warning list!!!

The (almost) perfect guide for buying a cellphone

1. Can you live without a smartphone?

If the only use of your phone is to make calls, text and grab a few snaps and you can live being ridiculed for the rest of the life for not having a smartphone by quipping I'm smart so i don't need my phone to be smart, well you might just survive. But if you really need on the move light weight access to your mail, your docs and want to kill your boredom on the move with really fancy top notch games, then definitely go buy one.

2. Where do you live?

The single most important factor that decides what kind of phone you buy besides the cost and your need is your geographic location. Say you live in one of the third world countries (read India) which is not likely to be covered by 4G network anytime soon you definitely don't need a 4G phone. (You can scratch out EVO4 and IPhone 4 from your list now) Now if you live in an rural area currently covered by 2G , do a gut check whether 3G will be available anytime soon. If yes then only go for a 3G phone. If no settle down for a 2G phone, i don't think you would require a smartphone even as with slower network connectivity because of old age technology like EDGE you smart phone would be practically useless.

Services and speeds _{(courtesy: cnet.com)}

	1G	2G	2.5G
Technology	AMPS	GSM CDMA iDen	GPRS 1xRTT EDGE
Speeds	n/a	Less than 20Kbps	30Kbps to 90Kbps
Features	Analog (voice only)	Voice; SMS; conference calls; caller ID; push to talk	MMS; images; Web browsing; short audio/video clips; games, applications, and ring tone downloads

	3G	3.5G	4G and beyond
Technology	UMTS 1xEV-DO	HSDPA (upgrade for UMTS) 1xEV-DV	WiMax*
Speeds	144Kbps to 2Mbps	384Kbps to 14.4Mbps	100Mbps to 1Gbps
Features	Full-motion video; streaming music; 3D gaming; faster Web browsing	On-demand video; videoconferencing	High-quality streaming video; high-quality videoconferencing; Voice-over-IP telephony

*WiMax has been mentioned as a possible 4G technology, but no standards have been set.

3. What kind of hardware should your phone have?

The most important factors of the phones performance are its processor and its RAM. So you tend to think if the number of MHz (or GHz) of your phones processor is more then its certainly faster right? So what is there to think about it, you may presume? Well, you should really think about how much processing you require as faster the processor the more it drains your battery. If you would never play angry birds on your phone, and all you need are docs and email you dont really need to go for the 1, 1.2 Ghz monsters. But yes if HD games are for you then definitely check the spec sheet whether the phone has an add on GPU as well. And about RAM yes the higher the better (try the latest iNand maybe)

4. The brand factor....

So if the single factor that made you think you need a smartphone is that you want to show off to the gullible folks around  and you don't really care about performance, stop reading and go get a skin deep iphone.







5.Which operating system should your phone have?

a) Apps
So you shelled 20-40K INR on your phone. Then you need apps to do all the fancy stuff the phone boasts it can do. So you log on to the app store and you see every app you need tagged with a 10$ fee. Damn irritating rite? If you don't have all the money on the planet to invest on apps and don't really want to bear the burden of piracy  settle for a droid which has lots of free apps and open source support. If you have the money, well decide you want to see the same windows that adorns your computer choose a winphone or you want something trendy read the brand factor :P

b) Upgradability

So the company manufacturing your phone added some cool stuff to the operating system. They made it smarter smoother and power hungry. And now they are putting it on all new phones and you can't get it on yours. Congratulations the brand new phone you bought 6 months ago is outdated. Now you wouldn't have to deal with this if you are an android user. You can always upgrade and if you are the one who doesn't like change often stick to a winphone or an iphone.If you are a total geek who wants to push more and more into your phone get a droid. {for example my HTC hero came with android 1.5( with no bluetooth support even darn) and today i run android 2.3.4 in it (Bluetooth stack, DSP sound effects etc are few new features that were never in my phone when i bought it)}

6. Battery life

This is something most people ignore but trust me its really painful when you are on the move and your phone runs out of juice. Other than making the right hardware choice also look for power saving features in the phone like automatic brightness control, wifi sleep policy controls and the like so that you can keep your phone running longer. You don't want it to switch off when you are expecting the most important call of your life right?







7. Can you still make phone calls?

There is no use having a phone regardless of  its smart factor if you can't make phone calls with it.
 IPhone Antenna Issue

Hello world!

Its all in the syntax, whats your favourite?

C

include<stdio.h> main() { printf("Hello World");}


C++


#include <iostream> void main(){ cout<<"Hello World";}


JAVA


class HelloWorldApp { public static void main(String[] args) { System.out.println("Hello World!"); //Display the string. } }


PYTHON/PERL


print "Hello World!";


RUBY


puts 'Hello World!'


FORTRAN


Program Hello
    Print *, "Hello World!"
End Program Hello


ABAP


REPORT TEST.
WRITE 'Hello World!'


COBOL


IDENTIFICATION DIVISION.
PROGRAM-ID. HELLO-WORLD.
PROCEDURE DIVISION.
         DISPLAY 'Hello, world!'
         STOP RUN.
GO


package main


import "fmt"


func main() {
     fmt.Println("Hello World!");
}


ERLANG


-module(hello).
-export([hello_world/0]).
hello_world() -> io:fwrite("Hello World!").

JAVASCRIPT

<script type="text/javascript">
      document.write('Hello World!');
    </script>

Q

hello = writes "Hello World!";

SHAKESPHERE (I ll never code in this ever )

This is part of the standard "Hello World" program in SPL. The statements assign numerical values to the other character, and "Speak your mind" is an order to the other character to output that value as a character.
Romeo, a young man with a remarkable patience.
Juliet, a likewise young woman of remarkable grace.
Ophelia, a remarkable woman much in dispute with Hamlet.
Hamlet, the flatterer of Andersen Insulting A/S.

                   Act I: Hamlet's insults and flattery.
                   Scene I: The insulting of Romeo.
[Enter Hamlet and Romeo]
Hamlet:
You lying stupid fatherless big smelly half-witted coward! You are as
stupid as the difference between a handsome rich brave hero and thyself!
Speak your mind!
You are as brave as the sum of your fat little stuffed misused dusty
old rotten codpiece and a beautiful fair warm peaceful sunny summer's
day. You are as healthy as the difference between the sum of the
sweetest reddest rose and my father and yourself! Speak your mind!
You are as cowardly as the sum of yourself and the difference
between a big mighty proud kingdom and a horse. Speak your mind.
Speak your mind!
[Exit Romeo]
                   Scene II: The praising of Juliet.
[Enter Juliet]
Hamlet:
Thou art as sweet as the sum of the sum of Romeo and his horse and his
black cat! Speak thy mind!
[Exit Juliet]
                   Scene III: The praising of Ophelia.
[Enter Ophelia]
Hamlet:
Thou art as lovely as the product of a large rural town and my amazing
bottomless embroidered purse. Speak thy mind!
Thou art as loving as the product of the bluest clearest sweetest sky
and the sum of a squirrel and a white horse. Thou art as beautiful as
the difference between Juliet and thyself. Speak thy mind!
[Exeunt Ophelia and Hamlet]

                   Act II: Behind Hamlet's back.
                   Scene I: Romeo and Juliet's conversation.
[Enter Romeo and Juliet]
Romeo:
Speak your mind. You are as worried as the sum of yourself and the
difference between my small smooth hamster and my nose. Speak your
mind!
Juliet:
Speak YOUR mind! You are as bad as Hamlet! You are as small as the
difference between the square of the difference between my little pony
and your big hairy hound and the cube of your sorry little
codpiece. Speak your mind!
[Exit Romeo]
                   Scene II: Juliet and Ophelia's conversation.
[Enter Ophelia]
Juliet:
Thou art as good as the quotient between Romeo and the sum of a small
furry animal and a leech. Speak your mind!
Ophelia:
Thou art as disgusting as the quotient between Romeo and twice the
difference between a mistletoe and an oozing infected blister! Speak
your mind!
[Exeunt]


More comprehensive list-> http://en.wikipedia.org/wiki/List_of_programming_languages

FlashBack - Part 1

Some days like today have driven wierd feelings into my life. I just felt like throwing away my laptop as my train of thoughts ran out of control. Dropped my phone and just fell on my bed, I wanted to sob but my tears were dry, wanted to cry out loud but my voice was dead..... This is the irksome feeling I have everytime I remember my mom. Life as an engineering student has had its positives and negetives, but as gadgets and technology exploded into my life of brittle relations held by tweets and texts I have lost the very meaning of what it means to be loved and cared for.

When I was a kid I was really eager to grow up, scale heights and be well "grown up" Today tough when I remember the bruised knees I had when I first fell off my cycle, I realise that those are much better than the wounded hearts that we carry. As a kid, you needn't worry about that unanswered question as your mom will always be there for you, to tell you what is right and what is wrong and why. She will always be there breaking your fall, savouring your rise, tending your heart giving you the essence of life called hope. Life was much simpler as 1+1 was always 2, and as some of my friends pointed out trees had leaves above and roots below the ground (unlike the 1+1=10 and binay trees) A friends smile was enough to tell he was happy, not a smiley on the text or a facebook status update. As a kid I could always turn to my mom to listen to me, but today broadcast to hundreds of "friends" on facebook, twitter and text but all are deaf and nobody cares.Thats the grown up world for you young kid, you gotta "grow up". There aren't people to listen to your problems, they've got their own, and you've to find your own source of hope.

What I sincerely miss though are few fingers ruffling through my hair and telling me that everything is gonna turn okay, that the sun will rise again tommorrow and that this too will pass......

How to Add a Facebook Apllication to your profile page?

Step 1: Login to facebook.com

Step 2: Get the the application you want to use. Our example here is http://apps.facebook.com/impetusapp/

Step 3: Click on view my profile from your facebook home page. Snapshot below shows where you can find it.



Step 4: Click on the "+" symbol on the tabs.

Step 5: Enter the name of the application you want to add.

Step 6: And voila. We are done :)