Sage is a free open-source mathematics software system. It combines the power of many existing open-source packages into a common interface. In order to tap the full potential of Sage, follow these simple steps:

• Enable cookies for your browser.
• Sign up for a Sage Notebook account at http://sagenb.org/register and sign in at http://sagenb.org/. (If you're behind a proxy or a firewall, make sure you're allowed connections to port 8000.)
• From the table of contents on the title page of the ECC Notebook navigate to the different chapters of the document, e.g. Chapter 2.
• In the very top left corner, click "Edit this" in order to create you own private copy of the worksheet. This is necessary so that you can have access to the full functionality of each worksheet, in particular to the interactive components.
• In some cases you may have to re-evaluate the worksheet. To do this, choose "Action -> Evaluate All" in the second drop down menu at the top.
• Some of the content uses special math fonts that are not installed by default on most browsers. When you notice that formulas are not displayed correctly or even get an error message about missing fonts from your browser, you need to install the jsMath fonts. Many browsers give you the option to install the missing fonts automatically. If this is not the case, you may download them here. The page also contains installation instructions.

Unfortunately, SAGE is a bit buggy sometimes. It is developing quickly and problems are fixed regularly, but for now, here are solutions to two common problems that you may run into. Firstly, some of the applications do not always work after opening a worksheet. Instead of nice output, they show lots of blue error messages. In such a case, simply click on the gray "%hide" above the program and execute the code again by typing "Shift+Enter". Doing this once or twice should solve the problem. Secondly, after doing this, the code does not always disappear. Instead, it sometimes turns gray. Should this happen, click on the gray text, then click somewhere outside of the text box. The code will then disappear and leave you with a nice layout of the worksheet.