Texas Instruments TITANIUM TI-89 User Manual

Page 767

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Activities

767

3. Use the

abs( )

function to find the absolute

value of

f(x+yi)

.

(This calculation may take about 2
minutes.)

Note:

The absolute value of a function

forces any roots to visually just touch
rather than cross the

x

axis. Likewise, the

absolute value of a function of two
variables will force any roots to visually
just touch the

xy

plane.

4. Copy and paste the last answer to the

entry line and store it in the function

z1(x,y)

.

Note:

The graph of

z1(x,y)

will be the

modulus surface.

5. Set the unit to 3D graph mode, turn on the

axes for graph format, and set the
Window variables to:

eye= [20,70,0]
x=

[

L

2,2,20]

y=

[

L

2,2,20]

z=

[

L

1,2]

ncontour= [5]

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