What does PLOT do?
The program draws a graph for any function that
can be entered as a formula in an Excel cell. This
graph will always be in a new sheet that it adds to the active workbook.
In addition to automating the steps required to create a graph in Excel, the
program adds an important refinement. It concentrates its efforts on those
parts of the graph with the greater curvature greater. The value of this
feature is best illustrated by showing the results for a very important
function, the LOG function. Plotting
for values between x = 0 and x = 10, the results are:
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Using the PLOT software
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Using more traditional means
such as an Excel Table
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The left-hand figure is from the PLOT
software. Note that the density of points in the region from x = 0 to x =
1 is much greater than that in the region from x = 1 to x = 10. This is
because the PLOT software concentrates its effort in the region where the graph
is curved rather than where the graph 'straightens out.' Keep in mind that
one needs only two points to draw a straight line, but a lot more effort is
required to draw a curved shape. This dynamic selection of x values
lets the software better define the shape of the LOG function for small values
of x.
For those who don't need this level of
sophistication in creating Excel charts, Stephen Bullen has an excellent
alternative to the use of an Excel Table. Look for the chtfrmla.xls file
on his web site (my web site at www.tushar-mehta.com
has a link to his site).
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