The two Data Set tab pages permit evaluation of functions f(x) in terms of the variable x. There are two Data Set pages so that users may make quantitative and qualitative comparisons between two data sets or functions. Each Data Set tab page contains an expression box, and a table region. The Data Set 1 tab page also includes a button that calculates and displays statistical information about that page's tabulated data.
Functions are entered in the expression box in a manner similar to that of the Evaluator's Expression Input Box. When a function is evaluated, a data table is generated. The table displays numerical values for the variable x, the function f(x), the first derivative f'(x), and the sign of the second derivative f''(x). The range and number of data points are determined from settings on the Plot tab page. Functions in the expression boxes are save d when the Calculator is closed and are reloaded the next time the program is started.
To explore the table of data values use TAB once from the Expression Input Box, then use the ARROW keys to move from cell to cell within the table. When moving between the columns of a table, the voice will say the name of the new column. Only the new data value will be spoken when moving between rows.
Alternative methods for data entry are to enter it directly into the table region or to import data from the File menu. A user may key data into the table and then compute data derivative information from the menu or with F4 hot key. This hot key will also update the visual and auditory graphs with any new or modified data. An external X-Y data table can be imported into the Data Set array by using the Import Data Set feature of the File Menu. Uncertainties (also called errors) can be included as a third column in the data file.
Statistical information may be obtained for data contained in Data Set 1 by selecting and pressing the "Statistical Description of Data Set button. This option is only available on the Data Set 1 tab page. After pressing the button, the contents displayed in the table changes to a scrolling informational window. By using the UP and DOWN ARROW keys in this window, you can scroll through the listed statistical information. The statistical listing includes the number of data points, sum, mean, and standard and sample deviations for both the X and Y data values.
In addition, there is information obtained from regression analysis of the data. Regression is used to fit a line or curve through a set of data points using a least sqares fit. The type of regression for data analysis is chosen from a separate list located below the data window. Types of regression analysis are Linear, Exponential, Logrithmic, Power, Hyperbolic, and two Rational functions. The equation used for the regression is listed along with the name. To change the method of analysis, TAB to the Mode field and use the UP and DOWN ARROW keys. The statistical information is automatically updated in the data display area.
There are two boxes for entering a test X or Y data point. Typing a test value into one of the boxes and pressing ENTER will change the focus to display the value for the other coordinate. The value is calculated using information obtained from the chosen type of regression analysis. A button that returns the user to the Data Table is located at the bottom of the page.
When data are loaded into both Data Set 1 and Data Set 2, the difference or sum may be plotted by selecting that option on the Plot tab page.
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Questions about the Accessible Graphing Calculator? Problems with the download? Send e-mail to: triangle@dots.physics.orst.edu
The Accessible Graphing Calculator was written by the Science Access Project at Oregon State University. It is Copyrighted and all rights are reserved.
Last modified February 14, 2000.