Knowledge Base

Solution 11835: Decreasing the Calculation Time Needed for the nSolve() Function on the TI-89 Family, TI-92 Family, and Voyage™ 200 Graphing Calculators.

How can I decrease the calculation time needed for the nSolve() function on the TI-89 family, TI-92 family, and Voyage 200 graphing calculators?

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 steps provided below:

• Use the program editor to define the 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.

Please see the TI-89 family, TI-92 family and Voyage 200 guidebooks for additional information.