Setting a Window - Finding One That Works. You can enter the dimensions of the graph by accessing button you will see a window like the one below.

Transcription

1 A. Overview 1. WINDOW Setting a Window - Finding One That Works You can enter the dimensions of the graph by accessing button you will see a window like the one below.. When you use this

2 The Xmin and Xmax values are the left and right endpoints (respectively) for the x-axis. The Ymin and Ymax are the lower and upper endpoints (respectively) for the y-axis. The Xscl and Yscl do not affect the graph. These are used to enter the increments for the tick marks. In the example above, there will be a tick mark at each unit. It is not necessary to have any tick marks, so you can set these values to 0. In fact, if you have too many tick marks you will get "an ugly graph". If you get an error message like the one below, you have not made the Xmin less than the Xmax or the Ymin less than the Ymax. To change the values in the window, just scroll down using the cursor and enter the values that you want. Unless you have a good idea of the window you want, using this method to find a good window can be time consuming and frustrating. There are several more efficient ways to find a window that are discussed in the next sections.

3 Overview 2. ZOOM The ZOOM menu offers you several preset windows. There are many times when one of these windows will work well with the function you are graphing.

4 1: ZBox 2: Zoom In 3: Zoom Out 4: ZDecimal This allows you to box in a particular area of the graph. Zooms in with the center at the point of the cursor. The default factor is 4. Zooms out with the center at the point of the cursor. The default factor is 4. This is one of the most useful windows. It is also called a friendly window because the TRACE key will move in increments of 0.1 with this window. The window size is X:[-4.7,4.7] and Y:[-3.1, 3.1]. 5: ZSquare 6: ZStandard Adjusts Xmin and Xmax so that the ticks are the same distance apart on both axes. This is also a useful window. The window size is X:[-10, 10] and Y:[-10, 10]. However, the TRACE does not move in increments of : ZTrig Sets the window to. 8: ZInteger Redefines the window to Xscl=10 and Yscl=10. 9: ZoomStat Gives a window that shows all statistical data points. 10: ZoomFit Sets a window that shows the maximum and minimum value of Y with the given X window.

5 Some of these presets can give you some strange results, so it is best to use just ZDecimal or ZStandard until you become more proficient when setting windows. Several of these are used in the examples in section B of this module.

6 Overview 3. TRACE The trace key can be used to help you set a window, but TRACE is most useful in graph analyses that is covered in Working With A Graph.

7 When you access TRACE, the screen will come up showing the graph, and the initial values will be in the middle of the screen. You can use the up and down cursors to trace to a value, or you can enter a value of x that is within the window. Note: If you are using the ZDecimal window, the trace will move in increments of.1. In other windows, you will find it better to just enter the value of x you wish to evaluate. You can use the cursor to trace to a value. You can enter a value of x in the TRACE window. You cannot enter a value of x that is outside of the interval, [Xmin,Xmax]. If you need to find function values outside of this interval you will have to use the TABLE.

8 Overview 4. TABLE The TABLE feature of the TI-83 and the TI-84 is one of the most powerful and useful in graph analysis and in finding a proper window for difficult functions.

9 Before you use the TABLE, you will need to access TBLSET and select the way you want your table to display values. You have two choices. i) You can have the table select the X value in preassigned increments and a starting point. Both the independent variable (Indpnt) and the dependent variable (Depend) must be set on Auto so that values are automatically generated. X starts at 0, increments of 1. X starts at -2, increments of -0.1.

10 ii) Most of the time you will want to be able to enter the values of X. This is useful in finding particular values of a function and in finding a window for the graph. Access the TBLSET and set the independent (Indpnt) variable to Ask, but leave the dependent (Depend) at Auto.