Texas Instruments TI-89 Tip List page 428

nSolve() (numeric solve) function algorithm
nSolve() uses a combination of bisection and the secant method, as described in Shampine and Allen
"Numerical Computing: An Introduction", W.B. Saunders Co., 1973.
nInt() (numeric integration) algorithm
nInt() uses an adaptive 7-15 Gauss-Kronrod quadrature somewhat like the algorithm described in
Kahanner, Moler and Nash.
Print history area on TI-92
You can save the entries in the home screen to a text file, send this to the computer and print it. To
save the history area as a text object, do the following:
! From the Home Screen, press F1.
! Select Save As....
! Give the text file a name.
You can then open this file in the text editor of the TI-92 or send it to the computer and print.
Number bases other than decimal on the TI-92
The TI-92 cannot work with numbers in bases other than decimal without a special program. Check out
the Soft Warehouse TI-92 Program Library for such a program.
The reason the TI-92 does not have this function is simply that the teachers we spoke with when
designing it thought that other functions were more important than base conversions/arithmetic.
nsolve() - why does it sometimes take so long to find a solution?
The nSolve() function uses symbolic techniques to simplify the equation before applying the search
technique. Depending on the equation, this simplification can take significant time. For example,
solving the Time-Value-of-Money equation for the interest rate can cause expansion of a high-degree
polynomial.
func-type User-defined functions are not simplified prior to the numeric search. Consequently, to avoid
the time-consuming simplification, use the program editor to define your equation in the following form:
:myeqn ()
:Func
: ... = ...
:EndFunc
Then on the home screen enter an expression such as:
nSolve (myeqn(), x)
Also, using the "with" operator to appropriately constrain the search range can greatly speed the
solution. For example, it is very important to restrict the interest rate to positive values when solving
the Time Value of Money equation for the interest rate, and it is also helpful to restrict it to be less than
some generously large number for a realistic interest rate.
Press ENTER twice in a dialog box to save settings - Why?
Dialog boxes can contain several user interface tools: text messages, drop down menus, and input
fields. Many dialog boxes require choices or input from the user on several lines before closing down
the box. We use the ENTER key to close down the box. So, for both drop down menus and input
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