Solution 11851: Summation or Sum() Function Algorithm on the TI-89 Family, TI-92 Family, and Voyage™ 200 Graphing Calculators.
What is the algorithm for the Summation or sum() function?
The sum() function uses iterated addition for numeric limits. Other sums are determined from formulas given in standard mathematical tables. Limits or special formulas are used for infinite summation limits.Please see the TI-89 family, TI-92 family and Voyage 200 guidebooks for additional information.