Texas Instruments TI-89 Titanium User Manual page 339

Be careful when using implied multiplication with
Enter: Instead of:
ù
tcos(60)
t cos(60)
When using
Note:
the command from the Home screen (see the Technical Reference module) to
Define
define functions and equations for any graphing mode, regardless of the current mode.
The Y= Editor maintains an independent function list for each
example, suppose:
• In FUNCTION graphing mode, you define a set of
PARAMETRIC graphing mode and define a set of x and y components.
• When you return to FUNCTION graphing mode, your
in the Y= Editor. When you return to PARAMETRIC graphing mode, your x and y
components are still defined.
Selecting Parametric Equations
To graph a parametric equation, select either its x or y component or both. When you
enter or edit a component, it is selected automatically.
Selecting x and y components separately can be useful for tables as described in Tables.
With multiple parametric equations, you can select and compare all the x components or
all the y components.
Parametric Graphing
Because:
tcos is interpreted as a user-defined function
called tcos, not as implied multiplication.
In most cases, this refers to a nonexistent
function. So the TI-89 Titanium simply returns
the function name, not a number.
, be sure implied multiplication is valid for your situation. You can use
t
. For example:
t
Graph
functions. You change to
y(x)
functions are still defined
y(x)
mode setting. For
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