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val it = [~2921] : int list
</pre>
=={{header|Stata}}==
It's possible to implement differences using row indices. For instance, first forward differences of a variable x can be defined by:
<lang stata>gen y=x[_n+1]-x[_n]</lang>
However, it's much more natural to use [http://www.stata.com/help.cgi?tsvarlist time-series varlists]. In order to use them, it's necessary to first set a ''time'' variable, which may be simply an index variable.
<lang stata>* First create a dataset
clear all
set obs 100
gen i=_n
tsset i
gen x=rnormal()
* Differences
display "Difference order?" _request(k)
gen y=D${k}F${k}.x</lang>
=={{header|Tcl}}==
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