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## Saturday, November 7, 2009

### Calculator Customization Using Transformations (Post #2)

If you follow the instructions from Post 1, you should have a drawing on your calculator screen. If you plotted points in Quadrant I, and set your window from -10 to 10 in both directions, the picture is in the upper right quadrant of the graphing window.

Part 3: Plot Transformations of the Drawing

Now we want to take our picture and transform it using the lists. For example, let's say I want to reflect the picture over the y-axis. Instead of graphing (x, y), I need to graph (-x, y). Go back to the lists in STAT, Edit. Put the negation of L1, the x-coordinates, into L3. You don't have to type them all separately. With the cursor, highlight the list title L3. Then type the negative sign (-) and L1 with 2nd, 1. Then Enter. It should automatically populate L3 with the negation of every value in L1.

We still need to graph (L3, L2) to graph the reflection. Go to 2nd, Y= (STAT PLOT). Turn on Plot 2. Now use L3 for the XList and L2 for the YList. Press GRAPH. You should see both your original picture, and its reflection over the Y-axis.

You can plot any transformation you like now by using L4, L5, and L6 in the same fashion. Plot (-L2, L1) for a Rotation of 90 degree counterclockwise. Plot (-L1, -L2) for a point reflection through the origin. Plot (L1, L2 - 10) to translate the picture down by 10 units. Etc etc.

This part is optional, but it is nice to add some text, like your name, if you are going to use the drawing as the start-up screen for the calculator.
1. If you are not already there, go to the GRAPH screen.
2. Press 2nd, DRAW, and arrow down to "Text". Press ENTER. You will see a flashing cursor on the graph screen along with your drawing.
3. Use the arrow keys to move the cursor to where you would like to start typing.
4. Hit 2nd ALPHALOCK to put the calculator in alphabetic mode.
5. Start typing your text. If you need a space, it's above the zero key. Press ENTER when done.
6. If you mess up, you can't delete mistakes. Unfortunately, you have to start over again. To start over, go to 2nd DRAW and select ClrDraw. Go back to step 1 in this section.