EC-4044 (650-0808) Operation Faxback Doc. # 3482 Resetting the calculator Using reset can select all default settings and clear everything. Because there are other ways to clear that affect only specific items, you should reserve the reset function for appropriate situations. You might choose to reset when you first purchase the calculator, or when required to in a classroom situation. Alternatives to Before you use reset, consider the other methods for Resetting clearing described on the next page. For example you can clear an individual formula without resetting. Reset Procedure When you press 3rd [RESET], the calculator exits from any sequenced entries or results and clears any entry in progress. Then: 1. The display shows Defaults YN? -> To leave the settings unaffected, respond N. -> To reset the six settings, respond Y. Angle unit resets to degrees. Default number base resets to decimal. Complex number form resets to rectangular. Digits of precision resets to 10 digits. Notation resets to standard. Fixed decimal format resets to floating. 2. The display shows Clr Mem YN? -> To leave memory intact and end the reset sequence, respond N. -> To choose to clear the memory, respond Y. 3. The display shows Confirm YN? This prompt gives you the chance to reconsider because memory may contain formulas or other data that would be difficult to restore. -> To leave memory intact and end the reset sequence, respond N. -> To clear all variables, formulas, and the statistics data set, respond Y. The message Cleared is shown. Clearing You can clear individual items or certain groups of items with the key sequences listed below. Methods of The following table helps you use the clearing Clearing features. Item to Clear Method Entry line Press CLEAR. An Incomplete fix or Rcl, but not Press CLEAR. other items of the current entry A value asked for in a prompt, but Press CLEAR. not the prompt Sequence of results Press any key other than <-, ->, = ENTER, 2nd [NEXT], 2nd [BACK], or STO. Statistics data set Press 2nd [CS] Y. An individual formula or variable Use 2nd [VAR] or 2nd [FMLA] to specify the name and press 3rd [CFV] Y. All variables Press 3rd [CVs] Y. Computational Accuracy The calculator achieves its accuracy by having more digits internally than are shown in the display. These extra internal digits guard against visible inaccuracies by keeping roundoff error past the 10th digit, and are called guard digits. You can select two ways for the guard digits to be used. Digits of The two choices for the digits of precision are: Precision -> 10 -digit - Results appear with up to 10 digits. Settings For calculations executed together in the same entry, 10 digit- precision keeps the guard digits until the answer appears, showing the same result as 13-digit precision. However, slight differences may become visible in successive calculations. The advantage of 10 digit precision is that most numbers are more compact in a subsequent calculation. -> 13-digit - Results appear with up to 10 digits, internally the guard digits remain to preserve accuracy. A number, when used in a subsequent calculation, occupies up to 13 digits in the entry line for the 13-digit setting, compared to a maximum of 210 digits in the 10-digit setting. To switch between 10-digit and 13-digit and 13-digit precision, press 2nd [13>]. Rounding a Result If a calculation produces a result that is more than 10 digits, the calculator uses the guard digits to determine how to display the result. -> If the first digit past the visible display is 5 or greater, the calculator automatically rounds the result to the next larger value in the last displayed digit. -> If the first digit past the visible display is 4 or less, the guard digits do not affect the displayed result. If 10-digit precision is selected, the internal value is replaced with the 10-digit rounded value after all calculations in the entry line are completed. If 13-digit precision is selected, the unrounded result remains for subsequent calculations. The Round The round function (rnd) rounds the internal value to Function 10 digits. If you use Rnd with a complex number, both parts are rounded. The syntax for rounding a number is: rnd number 1. Begin with the rnd function (3rd [RND]). 2. Follow it with the number or expression that is being rounded. To execute an entry, press =ENTER. Comparison of Consider the problem X 2.4207 x 2.165. The true Internal and result is 10.00000005555. Displayed Results The calculator shows 10.00000006 when set to floating decimal notation and has the following internal results. Internal result for 13-digit setting 10.00000005555 Internal result for 10-digit setting 10.00000006000 Internal result of rnd(1.9081 X 2.4207 X 2.165 10.00000006000 If the calculation is entered with rounding, the internal result is the same for either 10-digit or 13-digit precision. (br/all-12/12/94)