Subject Areas
Tools / Misc
  Math Tools

scrnGC2: Calc Input
scrnGC3: f(x) Plot Input
scrnGC4: g(x) Plot Input
The inputs above will be hidden when the program finally gets launched. Currently, I am not hiding them even when you close the calculator. The purpose of the inputs is to help in debugging. This allows you to enter simple code on the calculator screen but the program translates the input to javascript math. Give it a try and see if you notice any obvious problems or have suggestions for improvements.
Graphing Basics
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The purpose of this section is to show you how to plot a point and how to draw a line graph. Although there are various types of graphs, linear graphs do an adequate job of showing trends in data. Once you become proficient making linear graphs, you will find it to be an excellent aid in visualizing your data.

This section will only cover 2-dimensional graphing. This means that you can show your work on a sheet of paper as it is basically 2-dimensional. It does have thickness but one seldom writes on the edge of a piece of paper. Graph paper comes in various grid sizes. Typically, you select the grid size that will permit you to show all your data.

For purpose of illustration, we will make a very small graph, using a small 5x10 grid, as shown below.

The grid on the left is a 5x10 grid without scaling. The middle grid has been scaled from zero to five vertically (up and down) and zero to ten horizontally (left and right). Note that this is only one way of scaling this grid. The grid on the right has been scaled from zero to ten in both directions.
Start by plotting the point (7,3) on the middle grid. As you can see, the point is defined by two numbers. These numbers will always come as x-y pairs. The first number is the value for x and the second is the value for y. Xs denote how far left or right your point is. Ys denote how far up or down your point is. A point does not occupy any space and is generally shown as a + but for purpose of illustration, we will use a red dot ().
All points are relative to the origin, which is the point (0,0). It does not matter whether you go to the y-coordinate first or the x-coordinate. For consistency, it is recommended that you do it in the order that you see the numbers. The x-coordinate comes first and then the y-coordinate. Try to think of it as, "Going in the building and then up the elevator." Right and up is shown on the grid above. The green line indicates how we got to the final destination, (7,3).
Let us finish up by plotting six points on a grid similar to the one shown at the far right, above. Once we have plotted the points we will connect them with a straight line and we will have a line graph.
For this exercise we will plot the points, (0,4), (2,8), (5,2), (7,4), (8,6) and (10,4). The first grid shows the plotted points.


The second grid shows the points connected with straight lines.


The third grid shows the line graph without the dots because, remember, a point does not occupy any space.

Hopefully, this will give you a good start in plotting points and drawing linear graphs. Obviously, you have to be good at plotting points before you can make a line graph. Should you need practice plotting points, you may find this GED x-y graphing excercise helpful.

© 2002- John Schlecht. All rights reserved.