Game Development Reference
In-Depth Information
To set Visual Formula so that the lines and scales resemble those shown in
Figure 10.9, type
20 in the From field beneath the X Range label for the Chart
for Formula 1 button. In the To field, type 20. In the Chart panel, set the Zoom
values to
3. Set the Width fields to 2. If you click the Color fields, you can
choose the colors you find preferable from the color palette.
Absolute Values
The absolute value of a number corresponds to two values, one positive, the
other negative. Because the graphs you create using absolute values depict both of
these values, they are reflected across the
y
axis.
Here is an equation involving an absolute value that equates the absolute value of
x
with
y
:
y ¼jxj
For each value on the
y
axis, you find corresponding negative and positive values
of
x
. Figure 10.10 illustrates a graph of an equation that does not involve an
absolute value
ðy ¼ xÞ
. To the right of the graph of this equation, you see the
graph of an equation that contains an absolute value. The darkened arrow
emphasizes how the negative values of
x
generate positive
y
values. From this arises
a typical V representation of a linear equation that involves an absolute value.
You can employ Visual Formula to implement a linear equation involving an
absolute value. Use the following steps (refer to Figure 10.11):
1. Double-click the menu item for absolute values (Abs). Then click in the
equation composition area to position the absolute value bars. Use the
mouse cursor to pull the bars apart enough to accommodate a field.
2. Click menu item for Value, and then click in the equation composition area
to place the Value field between the absolute value bars.
3. Type an
x
in the Value field. The
x
represents a range of values Visual
Formula uses to generate a graph.
4. Now in the lower-right panel, click the Chart for Formula 1 button. (See
Figure 10.12.) The graph of the absolute value function appears in the
Cartesian plane.
5. To adjust the lengths of the lines you see graphed, click the X Range number
controls.
