Empty (Void) Elements; Calculations Involving Void Elements; List Arguments Containing Void Elements - Texas Instruments TI-Nspire Reference Manual

Empty (void) elements

When analyzing real-world data, you might not always have a complete data set. TI-Nspire™
Software allows empty, or void, data elements so you can proceed with the nearly complete
data rather than having to start over or discard the incomplete cases.
You can find an example of data involving empty elements in the Lists & Spreadsheet chapter,
under "Graphing spreadsheet data."
The delVoid() function lets you remove empty elements from a list. The isVoid() function lets you
test for an empty element. For details, see delVoid(), page
Note: To enter an empty element manually in a math expression, type "_" or the keyword
void. The keyword void is automatically converted to a "_" symbol when the expression is
evaluated. To type "_" on the handheld, press

Calculations involving void elements

The majority of calculations involving a void input will produce a void
result. See special cases below.

List arguments containing void elements

The following functions and commands ignore (skip) void elements
found in list arguments.
count, countIf, cumulativeSum, freqTable
max, mean, median, product, stDevPop, stDevSamp, sum,
sumIf, varPop, and varSamp, as well as regression calculations,
OneVar, TwoVar, and FiveNumSummary statistics, confidence
intervals, and stat tests
SortA and SortD move all void elements within the first argument
to the bottom.
/ _
4
list, frequency,
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