Applications

This page is a list of my own applications, equipped with screen shots as well as blurbs on how to use them!

Please check these out on the Android market when you get a chance!

- jwei

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Haiti Relief Widget (v 1.0)

$1.43

A simple widget that you can place on your home screen both to remind yourself of the tragedy in Haiti, and also to show others that you have supported the humanitarian effort in Haiti.

Why $1.43? Because Google takes a 30% cut so (0.7) ( 1.43 ) = $1.00 donated per application bought.

All proceeds will get donated this Sunday at my Church and will go to World Vision to help the relief efforts.

In times of tragedy, the world needs to come together.

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Implied Volatility Calculator (v 1.1)

$1.99 / FREE

For the Implied Volatility calculator, input the initial stock price, interest rate, volatility, maturity, strike price, and asking price, and it uses Newton’s method to find the implied volatility of that stock.

This application is for serious traders who want to quickly find out what the implied volatility of an underlying stock is based off of how the market is pricing its various options.

There is a LITE version, but in the Full Version, in addition to pulling the latest risk-free interest rate, you can import real time stock data (based on stock quote) and also real time option data (based on option symbol).

Calculated Implied Volatility

Developer’s Note:

This application was pretty fun to make because I got to actually use some of the stuff I learned in my latest MS&E class (Linear and Nonlinear Optimization) to implement Newton’s Method which would then help me go root hunting for the volatility.

Overall, there is a lot of pretty rigorous math that goes on in the background despite the simplicity in the design – but I guess that’s part of the appeal? Implied Volatility Calculator is definitely one of my favorite applications which I’ve made and so check out the free version if you’d consider yourself a trader and have heard of either the Black-Scholes model or what the concept of implied volatility is.

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Black-Scholes Options Calculator (v 1.0)

FREE

This calculator uses the Black-Scholes model to quickly calculate Option prices (European Call and Put) as well as the Greeks (Delta, Gamma, Theta, and Vega), and also provides graphs (courtesy of Google’s Chart API) which show the relationship of each with respect to the underlying stock price.

**Please comment on usefulness, as well as features you’d like to see in the future!

Input Screen

Graph of Options Prices

Developer’s Note:

This is my first actually useful application, and it’s geared towards a pretty specific audience (those who understand stocks/options enough to care about the Black-Scholes model). It can be found under the Applications/Finance section, and basically I recently took a course in Financial Mathematics and decided this would be a neat application to write.

To my surprise JAVA does not have a built in integral function (or maybe it does, but I couldn’t find it, in which case please let me know for the future) so I had to write my own. This was actually pretty fun as I spent most of my time trying to optimize the speed and accuracy, and basically my method for performing integrals simply involves calculating Riemann’s Sums at a certain step size to achieve a certain level of accuracy.

Any who, this application also uses the AsyncTask class from Android which you can read more about here:

http://developer.android.com/reference/android/os/AsyncTask.html

The example they give is actually pretty good, but in case you’re still confused let me know and I’ll write a little bit about how to implement this nifty feature.

And again, the application is totally free, so please take a look at it if you’re at all interested! I’m hoping to make even more improvements to this application soon!

- jwei

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Fart! (v 2.0)

FREE

An app perfect for killing time when you’re bored . Pick the type of butt you want (choose from Subpar, Average, and Sexy), give your phone a few good shakes, and let it rip! In the newest version, you can also choose from existing pictures in your photo gallery, and also take your own pictures and make those fart as well!

V2.0 Notes:

- New pictures added

- Two new features: set photos from your gallery as background, or take your own butt pictures!

- Reduced app size

*Note – shake until your phone vibrates

Selection Menu

V1.0 Average Butt

Developer’s Note:

Admittedly, this is a pretty stupid application, but I built it as more of a learning experience for myself. From a coder’s stand point, it allowed me to learn how to use and implement Android’s accelerometer features, as well as Android’s camera features in the latest version of the application. I also wanted to figure out how to actually export signed APK’s and publish them into the market, so just think of this application as my first little experiment.

Regardless, it’s free! So please check it out.

- jwei