Texas Instruments TI-92 Owners Manual - Page 355

Editing the Equation, Specifying an Initial Guess and/ or Bounds (Optional

Page 355 highlights

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. ¦ If the equation contains a system variable (xmin, xmax, etc.), that variable is not listed. The solver uses the system variable's existing value. In the standard viewing window, xmax=10. ¦ 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. For example, y1(x) is undefined and you use y1. Editing the Equation In the Numeric Solver, press C until the cursor is on the equation. The screen automatically changes to show only the eqn: line. Make your changes, and then press ¸ or D to return to the list of variables. Specifying an Initial Guess and/or Bounds (Optional) Tip: To select an initial guess graphically, refer to pages 340 and 341. 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. Initial guess must be within the bounds. For the bounds, you can also enter variables or expressions that evaluate to appropriate values (bound={lower,upper}) or a valid list variable that contains a two-element list (bound=list). The bounds must be two floating point elements with the first one less than or equal to the second one. 338 Chapter 19: Numeric Solver

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338
Chapter 19:
Numeric Solver
¦
If the equation contains a
system variable (
xmin
,
xmax
,
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
eqn:
line. Make
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 (
bound={
lower
,
upper
}
) or a valid list
variable that contains a two-element list (
bound=
list
). The bounds
must be two floating point elements with the first one less than or
equal to the second one.
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.
For example, y1(x) is undefined
and you use y1.
Initial guess must be
within the bounds.
In the standard viewing window,
xmax=10.