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Using a class is just as simple. When writing .your_class you style all tags with a class with the name “your_class”. In the example above we have .warning which will style e.g.

and , that is, any element with the class warning. Classes are used when you want to style just a few of your tags in a way, perhaps you want some of your links red? Add a class to all those links.

You need one more building block: the id. This time you style an element with the attribute “id” set to the id you have chosen. Ids work exactly like classes except for one thing; you can only have one id with a certain name in each of your HTML documents. In the example above we style

Tags: style, “id”, “your, class”, tags, ...
A trail of 2 pages

 From time to time people email me asking how to get started as a quant. While there are a number of fields that comprise the quant discipline and no list can be all-inclusive, if you are going to be interviewing for a quant position, you may wish to be conversant in the following areas: 

  • Finance and Financial Engineering, including complex financial derivatives and valuations, volatility surfaces and smiles, replication, arbitrage and equilibrium pricing models, CAPM, APT, Fama-French models and possibly risk management concepts depending on the area you’ll be supporting.
  • Statistics and Probability, at a fairly deep level with a good knowledge of distributions, maximum likelihood theory and perhaps empirical distribution fitting, tests for normality and fitting of joint distribution using tools such as copulas, how to perform out of sample tests, properties and expectation of random variables, correlation and covariance and so on.
  • Strong mathematics skills in areas including stochastic calculus, including martingales, markov processes (quick! What is the difference between a martingale and a markov process?), Ito’s lemma and so forth as well as ordinary calculus, differential equations, numerical methods, linear algebra and possibly a little computational complexity, algorithm analysis and optimization.
  • Econometrics – properties of ARCH, GARCH, detecting the order of an AR/MA process and so on, stationary and non-stationary variance and how to test and correct for the same if need be, transformations, random walks, unit root tests and so forth.
  • Knowledge of several computer packages, operating systems and languages including SAS, S-Plus, R, Matlab; expertise in a programming language such as C++, C# and/or Java, and experience with a non-Windows operating systems such as Unix.
  • Detailed knowledge of capital markets may be required, including understanding of credit derivatives, mortgage securities, fixed income and detailed knowledge of various interest rate models, depending on where you will be interviewing.
  • Understanding of simulation techniques such as generating simulations from various distributions and inverse transform theory, details of the Monte Carlo method and how simulation is used to value various financial instruments (also when you need to simulate as opposed to using other methods), possibly including variance reduction methods; random and pseudo-random number generation techniques, the pros and cons of various techniques, extreme value theory and so forth.
So where do you go to acquire this knowledge if you don’t already have it? Some good places to start are with free online MIT courses (and other universities) already discussed in a previous column. Some of the books that I recommend for your library include:
 
Financial Knowledge
You can get a great foundation in most of what you need to get started with John Hull’s book Options, Futures and Other Derivatives available on amazon.com and at other retailers. You can even get a student solution manual. 
 
Financial Engineering 
Baruch University professor Dan Stefanica has just come out with a great foundation book for most of what you’ll need to know and he has other books planned in this series. This type of book has been long needed.  There is a solution manual available as well!
 
  
Probability and Statistics 
I love the Schaum’s series for quick review. They’re inexpensive and comprehensive. There are a number of outlines including:
 
 
  
Time Series Analysis 
I recommend getting a copy of S-Plus and buying Ruey Tsay’s book, Analysis of Financial Time Series, and working through the examples. Professor Tsay, of the University of Chicago, has a lot of worked examples and solutions from the book on his website as well.
 
There’s a great time series book on University of Chicago Professor John Cochrane’s website, and it’s completely free:
 
Monte Carlo Methods 
The book by Paul Glasserman of Columbia University, Monte Carlo Methods in Financial Engineering (Stochastic Modelling and Applied Probability), is a classic in the field. 
 
If you buy these from Amazon, you can also often get a digital edition that you can view online from any computer. 
 
Stochastic Calculus for Finance 
There are a lot of great books for learning stochastic calculus,  but you can’t go wrong with Steve Shreve’s books:
 
 
 
Quantitative Interview Prep Books
There are books on finance and advanced finance interview prep, including my book from Vault.com, which should give you the basics. 
 
 
2) Vault Guide to Advanced Finance & Quantitative Interviews  (disclaimer: this is my book)
 
 
5) Quant Job Interview Questions and Answers, by Mark Joshi, Nick Denson and Andrew Downes. 
 
Matlab
Matlab is a powerful and widely used tool in quantitative finance.  The mathworks site has lots of sample code, examples and webinars.  There are some great free resources to help you learn this tool as well.  I have some of these posted on my blog in the Matlab category 

This should get you started.  Good luck, and if you have questions, just post them in the comments section.

Tags: including, calculus, probability, time, methods, ...
A trail of 1 page

I love the Drupal CMS. One of my favorite features of Drupal is the ability to do a multisite install. This site and my other blog, i <3 stella, are hosted on the same box, using the same Drupal install. Several sites can share one codebase. Updates are easily rolled out to every site simultaneously. Overall, it's a wonderful idea. But I have some problems with the implementation...

The standard way to set up a multisite install is to point each of the domain names at the Drupal install folder and let Drupal sort out which domain each request is coming from. It does a good job, too. But this method introduces some complications. For example, any content uploaded to site a is accessible from site b. A user that visits http://site1.com/myimage.jpg will find the same image as she finds at http://site2.com/myimage.jpg. Websites can't have domain specific .htaccess or robots.txt files either, which might hurt search engine optimization of individual sites.

An interesting side effect of this is if you want to install something in a subdirectory of your site, for example a WordPress blog at http://site1.com/blog, that exact same WordPress blog will exist in its full glory at http://site2.com/blog...

Another, and perhaps more grave, problem is that all that stands between the interweb and your very own personal settings is an .htaccess file. Install scripts, includes, site configurations and database passwords are in web accessible directories, and that is never a good thing.

We'll look at one solution to these problems.

I assume here that you are using Linux hosting, that you have shell access, and that you have at least a passing acquaintance with symlinks. If you're looking for a webhost that meets these requirements, check out 1and1 shared hosting. I've been happy with them, and all of their packages above $9.99/mo will do what you need.

Microsoft/IIS guys, you can't do a symlink. You're looking for something called a junction... good luck with that.

Tags: install, http, jpg, htaccess, multisite, ...
A trail of 29 pages