Sage

Sage is a free open-source mathematical software system designed to be an open source alternative to Mathematica, Maple, Matlab etc. It can plot functions, take derivatives and limits, integrate, and solve equations among many other things. Check out the Sage website if you are interested. You can use Sage from your web browser or download it for free onto your own computer (Linux, Mac, or Windows).

Instructions for getting started with Sage:

Open a browser, and go to reed.sagenb.org or to sagenb.org. First hurdle: signing in. One way to do this is to type your Reed email address in for the username. Then click on Google. Note: do not fill in the password on this first page. With luck, you will eventually be asked to sign in at Reed, and you should be presented with The Sage Notebook page.
Click on New Worksheet and give your worksheet a name. Click inside the cell (rectangle) and type 1+1. Click on evaluate of hold down the Shift key and hit Enter.
Now enter plot?. After a few seconds, you should see more than you want to know about the plot function. I usually skip through the documentation looking for examples. Try plotting something.
Next potential problem: getting 3d-rendering working in your browser. Try entering
```
var('x,y')
```
```
plot3d(x^2+y^2,(x,-1,1),(y,-1-1))
```
Then click on Make Interactive. I tried this on three different browsers in the ETC. For each one, I needed to click on something to get the appropriate plugin to load. After doing this, I needed to restart the browser (at least with Firefox). With Chrome, I was told that I needed to give java permission to run. There was a button that appeared at the top of the browser (which I did not notice at first—argh!) that gave this permission.
In order to get the images of 3d plots in the notebook to print, click on Toggle Advanced Controls, then click on Get Static Image to Save. You can then choose Print from the menu on your browser.

Pointers:

To multiply, use *. Thus, the correct syntax for 2x+1 is 2*x+1.

Tutorials:

Go to the Sage website, and follow the link under Documentation to the the Tutorial.
From the Documentation page, you will also see a link to the SDSU Sage Tutorial.
For a more in-depth introduction, you could take a look at Sage for Power Users.

To email your Sage notebook:

From your Sage notebook, choose "Save worksheet to a file..." from the File menu.
Choose a descriptive name for your worksheet when asked. If you are turning in the notebook as part of a homework assignment, please include the homework number (for example, "HW4").
Save the notebook to your computer. The extension of the resulting file will be sws.
Attach the sws-file (saved notebook) to your email. If homework, send to davidp.classes (at) gmail.com.

To upload a Sage worksheet (sws file):

Either download the sws file or find its URL.
Open the Sage notebook.
Click on Upload near the top of the page.
Either Browse you computer for the downloaded file, or fill in the frame asking for the URL.
Click on Upload Worksheet.