Texas Instruments TI-89 Manual Book page 355

Note: You cannot solve for
a system variable other than
exp . Also, if the equation
contains a system variable,
you cannot use ... to graph.
Note: This error occurs if
you use a reserved name
incorrectly or refer to an
undefined system function
as a simple variable without
parentheses.
Editing the Equation
Specifying an Initial
Guess and/or
Bounds (Optional)
Tip: To select an initial
guess graphically, refer to
pages 340 and 341.
338 Chapter 19: Numeric Solver
¦
If the equation contains a
system variable (
xmin
etc.), that variable is not
listed. The solver uses the
system variable's existing
value.
¦
Although you can use a
system variable in the
equation, an error occurs if
you use ... to graph the
solution.
¦
If you see the error shown
to the right, delete the
entered variable value. Then
edit the equation to use a
different variable.
In the Numeric Solver, press C until the cursor is on the equation.
The screen automatically changes to show only the
your changes, and then press ¸ or D to return to the list of
variables.
To find a solution more quickly or to find a particular solution
(if multiple solutions exist), you can optionally:
¦
Enter an initial guess for
the unknown variable.
The guess must be within
the specified bounds.
¦
Enter lower and upper
bounds close to the
solution.
For the bounds, you can also enter variables or expressions that
evaluate to appropriate values (
variable that contains a two-element list (
must be two floating point elements with the first one less than or
equal to the second one.
, ,
xmax
In the standard viewing window,
xmax=10.
For example, y1(x) is undefined
Initial guess must be
bound={lower,upper}
bound=list
and you use y1.
line. Make
eqn:
within the bounds.
) or a valid list
). The bounds