Wednesday, October 31, 2007


How difficult is it to unlock iPhone? The start up screen says it all (Slide to Unlock, LOL).

Seriously though, when you need to utilize a buffer overflow exploit and SSH to replace system files on a cellphone, it's definitely not for the faint hearted. Here is a comprehensive guide on jailbreaking and unlocking iPhone with firmware 1.1.1 on Windows. A word of caution: the guide may not be completely up to date and, needless to say, you're risking voiding your warranty and bricking your iPhone.

it's comforting to know that in most cases, you can set iPhone to recovery mode and restore the default settings (Turn off, hold Home key and plug the USB connector. iTune will deal with the rest).

Thursday, October 25, 2007

Grid Computing in .Net

CDO Pricing: Binomial Expansion Technique

BET is a relatively simple technique used by Moody's to price and rate CDOs.

  • First, the collateral pool is mapped to a hypothetical portfolio of N uncorrelated assets (the diversity score).
  • The default probability of assets in the hypothetical portfolio is then calculated with WARF (Weighted Average Rating Factor)
  • .
  • Since the default event of each asset is uncorrelated, the probability of J defaults in the portfolio simply follows binomial distribution: (DS: diversity score. PD: probability of default for each asset)
  • With this distribution, the expected loss (EL) for each CDO tranche can now be calculated: (Lj: loss for a given tranche with J defaults)
  • The expected loss can now be used to price or rate the CDO tranche by referencing comparable securities (i.e. with similar default probability).

The BET methodology gives a sneak preview of what's deep down in the CDO pricing rabbit hole without getting into the rocket sciences (Monte Carlo, Copula, etc). Here is a good paper that compares the BET with Monte Carlo simulations.

Tuesday, October 23, 2007

Windows 7

A demo of the next generation Windows kernel, strip naked, codenamed "Windows 7" (Microsoft really needs to put more work in these names. Just a random thought, something along the line of "iWin" might work...).

The OS ran under Virtual PC, and this allowed Traut to show the audience exactly how many resources it was consuming: about 25MB on disk (compare with 14GB for a full Vista install) and 40MB of RAM. The OS booted up in about 20 seconds inside Virtual PC.

Friday, October 19, 2007

Dow down more than 366 points

A nice way to pay tribute to the 1987 crash on its 20th anniversary.

ClickOnce Resources


The big boys are putting togather an $80b mega fund, dubbed M-LEC, or Master Liquidity Enhancement Conduit, to prevent a melt down in asset backed commercial paper market by purchasing assets from troubled SIVs.

JPMorgan is quick to confess that it has no direct exposure in such SIVs. So it's into this only for the "greater good" (read: fees).

Tuesday, October 16, 2007

About Goldman's blowout quarter

As Goldman's official 10Q filing has come to light, some started to rise questions about its spectacular third quarter earnings.

The focus is on the $2.6b unrealized level 3 trading gains Goldman booked for the quarter, a category that has been called "mark-to-make-believe" by some analysts.

So does Goldman really stand head and shoulders above its peers? Only time will tell.

Friday, October 12, 2007

Certified Scrum Master

Got certified this passed weekend. The training course was taught by Ken Schwaber, the master himself. The case studies were very well organized, the benefit and challenge of implementing Scrum in an organization are cleared delivered to the trainees.

That being said, there is the part of me that doesn't completely agree with the "certification" process. Base on my observation, there are about a third of the trainees either have no clue about Scrum or have only read about it on paper. Another one third implemented some half baked version of Scrum (i.e. Backlog but no daily Scrum meeting, Assigned ScrumMaster but no clear role of product owner, etc). And only the one third left being hardcore Scrum practitioners. Besides, there is really nothing stopping one from have nice chats with people during the two days, enjoy the food and "woof" your way out of the door being "certified". It's hard to believe that all these people can now take the responsibility of being the change proxy for the organization. In my mind, being "certified" implies there is going to be a bar set to be cleared. Well, maybe it's just me...

Thursday, October 11, 2007

WPF: Interactive 2D Controls in 3D space

The power of WPF really has no limits. With just a little help, you can place 2D controls (text box, button, you name it...) on to 3D space. The coolest of all, these controls are fully operational!

The source code download contains a couple examples in XAML as good starting points.

What's under the hood.

Monday, October 8, 2007

Notes on the infrastructure of WPF

A Four hour train ride to Boston is the pefect timing to do some catch up reading on WPF, and there had been a few thoughts popping up somewhere in Conneticut and Rhode Islands. Some notes to check on later:

  • The entire Dependency Properties, Attached Properties and Routed Events framework is great. But what does it take to move these components out of the WPF framework and into your application? How much do they depend on WPF (UIElements, etc)? I know this is not easy, as WF has got a separate system for it.
  • As the same time, this framework is actually bringing C#/.Net many steps closer to a scripting language (I.E. objects are no more than a group of loosely typed hashtables). Is there any real disadvantage to this approach, aside from performance?
  • The Automation Peers are more than a natural way to perform unit tests on GUI components. Are there any related products/frameworks available from Microsoft or someone else?

Thursday, October 4, 2007

Warren Buffett's comment on Investment in Gold

Read this from someone's blog today:

If Martian were to to observe the activity of human beings for many many years, they would not understand what these humans were doing. They are digging the gold out from the ground, proccess them and put them in the vaults and never touch them again.

A true value investor should only invest in businesses Martians can understand.

Wednesday, October 3, 2007

.Net Framework Library Source Code

Microsoft is releasing the source code of a host of .Net Framework Libraries with .Net 3.5 and VS 2008, according to ScottGu's blog here.

Now we fellow developers will have the mighty power to walk all the way up on the call stack. This is simply fantastic.

Debugging System.Threading.ThreadPool:

The next "Big" Flat Panel TV is ... 11 inchs

Sony will start to sell the first commercial OLED TV this december. The 11 inch TV is only 3mm thin and has a contrast ratio of 1,000,000:1. It has get fairly good reviews on picture quality, but the screen size is just too small.