Use Sage and Sell Your Calculator Before It Is Too Late

This is an introduction to a piece of software called Sage that will allow you to sell your calculator ( assuming, of course, that you have a calculator ) and still do your calculations more easily than with your calculator ( you will need a computer, but if you are reading this perhaps you have one).  If you wait till everyone else figures this out it will be to late, calculators will be too cheap.

What Sage can do ( and some calculators can do some of these things )

     * Use algebraic symbols.
     * Record the calculations so they can be edited and rerun ( if for example you make a mistake or want to do a closely related calculation.
     * Save the calculation as a file ( which can be shared with other, or recalled by you).
     * Use cut and paste in manipulating the calculations.
     * Plot your calculation  ( you can even extract the plot as an image ).
     * Save values to memory for recall, as many values as you want, and with meaningful names
     * Use scientific notation ( also know as power of ten notation ).
     * Print the results.
     * Let you program in python in a very easy way.

Most of the space in this instructable is taken up with setting it up.  To cut to the chase and see how it works view the attached pdf file.  After viewing the file you may have more incentive to install it.

Sage really wants to run in Linux, if you use Linux you can probably easily go to the Sage site on the web find a version, download it and install.  Since the Mac OS is similar, it is also pretty much at home on the Mac.  Until recently Windows was a problem.  That has been fixed, at least for those of us with Windows 7 on a reasonably hefty machine.  I am only going to cover Windows, perhaps someone else will do an instructable on the other OS's.  This may also work on XP and Vista, but I have not actually tried it.  My computer is a year old i7 with 8 gig memory and Windows 7.

You will want a Linux machine for your install.  If you have a Windows machine, you get this for free with a program called VirtualBox.  It turns your compute into multiple computers ( at the same time ).  Your computer is still Windows, but it also has other computers running on it with potentially other operating systems ( there are many uses for this, only running Sage will be covered here ).

Go to https://www.virtualbox.org/wiki/Downloads and download the version that best fits you computer.  Installing it is just running the download exe and tweaking a few details if you do not like the defaults ( if you do not understand the choices stick with the defaults ).  After installing run it.  You should get something like the screen shot above ( without the 2 virtual machines shown in my installation )

The Sage website has a virtual machine ( for VirtualBox ) that you can install easy as pie. Get it at: http://www.sagemath.org/download-windows.html where you will also find a link to installation, some of which I will repeat in the next step here. Remember where you put the file ( always a good idea when downloading ).

Run VirtualBox. When it comes up just choose: Import Appliance... then follow the prompts, you will use the file you imported in “Get the Sage Virtual Machine”.  

With virtual Box running highlight the Sage Virtual machine and press the Start button at the top of the window. A new window will open and you can watch the virtual machine start ( boot ) up. After the virtual machine is started, Sage will start up in it ( you do not have to do anything, watch if you want ). It is fully started when you get a line something like: Starting factory <twisted …..

You use the Sage Notebook through your browser.  Here I am going to use Chrome, but it seems to work with most browsers, all the ones I have tried.  Open the browser and go to http://localhost:8000 and you will get the administrative window for Sage which lists all your worksheets ( for me a lot, for you none ).  Press new worksheet and you will get one with a dialog box to rename it from Untitled to something more meaningful like My First Worksheet.  The worksheet has a very useful Help choice at the upper right.  Try it soon ( or now ) especially if you get stuck.  But for now lets do some math.

Wait a minute:  To really understand this instructable you should either open the attached PDF and read along in it ( it includes the Sage input and output ) or actually run the attached Sage worksheet.  To get the worksheet into Sage you need to: start a new worksheet, then use the File => Load Worksheet option.   Note that downloaded files from instructables have odd names, you may want to rename them to something more reasonable.

( Second Cell in Worksheet )  Add up some numbers. You will see a box in the worksheet ( called a cell ) this is for you to type in. Lets type  “5 + 7 + 22 +33.6 + 99”  At the bottom of the cell is a line marked “evaluate”  Click it, to the left will appear a vertical green bar ( means that the system is busy ), the bar goes away and 166.600000000000, the total appears.

( Third Cell in Worksheet )   Here we do the same total but save it in the worksheet memory as mytotal.

A bit of explanation.  The first line does the addition and saves it in a memory location called “total”.  The mytotal on the last line causes the total to be printed.  In general any value on the last line is printed.  Usually I do it more explicitly by typing print “mytotal”.

I could describe more, but instead why not get the file  … and read it in Sage or if you do not have Sage installed as the PDF.

Google will be your friend, but beware that much of the material is pretty high level stuff, you will need to filter out a lot.  There are other things on the web ( even software ) so try Sagemath as a keyword.

There are some public servers out on the web you can use, but I am not going to tell you where they are or encourage you to use them as generally they are already overloaded and the experience is often not good.

If your comments ask for more help that is not too difficult, I will add to or edit this instructable.