Application Guide

236 Empty (Void) Elements
Empty (Void) Elements
When analyzing real-world data, you might not always have a complete data set.
TI-Nspire™CAS 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 49, and
isVoid(), page 95.
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►list, frequency, 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.