Next week sees the start of two new Udacity courses in its Computer Science curriculum, one on numerical methods; the other on software debugging. Meanwhile if you've been waiting for the Pearson VUE exam for CS 101, it is now available.

When we spoke to Sebastian Thrun in June he confirmed that Udacity plans to provide a complete Computer Science degree curriculum, saying that new courses would come available with each passing seven-week term, referred to as a "hexamester" as there are six per year.

As Udacity enters its 4th hexamester there are three additions to the line up of Computer Science courses, all at Intermediate level, which are described below.

This brings the number of CS offerings to twelve; CS101 at an introductory level, eight courses that build on this foundation and are grouped in the intermediate caregory and three that are billed as advanced, including Peter Norvig's Design of the Computer Programs (CS212) that many of us, me included, assumed would be intermediate.

All Udacity courses are free of charge (no change) and are now "open", which according to the Udacity website:

means you can sign up any time and complete the course at your own pace without problem set or exam deadlines.

This is a change since the inaugural set of courses and not all "Udacians" are happy about it. While not having deadlines may reduce stress, it also removes the incentive to stick to a regular timetable. More importantly it means that you can't rely on finding other students experiencing the same problems at the same time. The discussion forums for Udacity courses give students a sense of community as well as providing answers to question and dealing with administrative issues and rely to some extent on having a cohort moving through the course at the same pace. Several comments from active students suggest that this change caters for those who dropout rather than for the ones who stay the course.

Let's look at the latest courses that have Premiere status - which means that all the material may not yet be available.

Making Math Matter: Differential Equations in Action (CS222) is taught by Jörn Loviscach, a professor of technical mathematics and computer engineering who has published over 1800 video lectures on his YouTube channel.

The course, which opens on September 3, is billed as examining real world problems involving differential equations and learning how to solve them using numerical methods and invites you to "rescue the Apollo 13 astronauts, stop the spread of epidemics, and fight forest fires". Prerequisites are programming at the level of Udacity's CS101, high school trigonometry, vector algebra, "exposure to calculus" and also to physics (a requirement filled by doing Udacity's PH100.

A course on debugging (CS259) also starts on September 3. Taught by Andreas Zeller, a computer science professor at Saarland University, Germany, it will teach students how to debug programs systematically, how to automate the debugging process and build several automated debugging tools in Python. It's promo videos makes this course attractive to anyone who spends too much time debugging.

CS259 requires knowledge of programming and Python, specifying CS101 or better plus basic knowledge of object-oriented programming for which a tutorial is provided.

The third new computer science course, Intro to Theoretical Computer Science: Dealing with Challenging Problems (CS313), taught by Sebastian Wernicke, looks at really tough topics such as NP-completeness -- and what they imply for solving tough algorithmic problems.

Although listed as "Intermediate" you need to have an understanding of algorithms from CS215 as well as programming.

While Udacity is not going to offer courses in the humanities, it isn't just about computer science. Steve Blank's course How to Build a Startup: The Lean LaunchPad begins on September 14. This is one of two courses in entrepreneurship originally on the list of "Stanford" courses that were postponed in January 2012. As it looks at how to build a successful business, it is of obvious relevance to Udacity students who want to "go it alone" into a career.

According to the Udacity blog, Udacity's Career Team has now helped several students find employment and from an initial 12 employers it now has over 400 companies interested in hiring Udacity students. Job placement is part of Udacity's business plan - it intends to provide free classes but hopes that matching successful students with employers will provide it a source of revenue.

This pool of potential employers provides some validity for Udacity education and the new opportunity to take a formal, "proctored" exam is another way in which Udacity is providing certification that will be accepted by employers other academic institutions. An exam covering the content of CS101 is now available at Pearson VUE centers around the world. The exam lasts 75 minutes, but you should allow 2 hours in total, and costs $89. The Udacity blog mentions the prospect of a secured online examination that will be less expensive than the in-person exam "in the very near future". And of course, even with the "open" format, once you complete the course and take the final exam you can print out your Certificate of Accomplishment.