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13.9.1 Drawing the Graph

To draw a polar graph:

  1. Create a new spreadsheet, saving the contour spreadsheet as contours.

  2. Enter the following data into the new spreadsheet:

    A B
    1 0.157 1
    2 0.314 2
    3 0.471 3
    4 0.628 4
    5 0.786 5
    6 0.942 5
    7 1.100 4
    8 1.257 3
    9 1.414 2
    10 1.571 1

  3. Select the range A1..B10. The columns will now be highlighted.

  4. Select New Graph from the Graph menu and display its submenu.

  5. Select Polar Graph from the New Graph submenu. NExS displays a window containing one-quarter of a crudely-drawn four-leaf clover as shown in Figure 13.18

You may not understand the relationship between the numbers and the plot, but notice that you created the graph in the same way you made a line or bar chart. However, the X data in column A is actually the angle with respect to the positive X axis. A value of zero in this column would cause data to be plotted along the X axis, while a value of approximately tex2html_wrap_inline15879 (1.571...) would plot data along the Y axis. Values between 0 and tex2html_wrap_inline15879 plot data along rays between the X and Y axis.

The distances along these rays at which the data points are placed are determined by the values in column B (which would be the column of Y data if this were a line graph). The data values in column A are an increasing sequence of angles with respect to the X axis, and the values in column B increase then decrease to move the plotted points away from and then closer to the graph origin. This creates the crude clover leaf.

   figure5181
Figure 13.18: Polar Graph

For polar graphs, the angular measurement and radial components correspond to the X and Y coordinates in a line graph, respectively. With this perspective, you can manipulate polar graphs just as you would line graphs. In fact, all the options available with line graphs can be used with polar graphs except:

  1. You can not display a label on the Y axis.

  2. If you annotate a polar graph, you must specify the point at which the annotation text is printed in (X,Y) coordinates, not in the tex2html_wrap_inline15883 notation that is used for the data.

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NExS User's Guide, Version 1.4.5
Grey Trout Software
11 April 1999