The numelems( ds ) command returns the number of elements in the DataSeries ds.

The lowerbound( ds ) command returns the index, which is always equal to 1, of the first element of the DataSeries ds.

The upperbound( ds ) command returns the index of the last element of the DataSeries ds.

Note that, for a DataSeries ds, numelems( ds ) is equal to upperbound( ds ).

$\mathrm{ds}≔\mathrm{DataSeries}\left(\left[\sin \left(x\right)\,\cos \left(x\right)\,\tan \left(x\right)\right]\right)$

$\mathrm{ds}≔\left[\begin{array}{cc}1& \sin \left(x\right)\\ 2& \cos \left(x\right)\\ 3& \tan \left(x\right)\end{array}\right]$

$\mathrm{numelems}\left(\mathrm{ds}\right)$

$3$

$\mathrm{lowerbound}\left(\mathrm{ds}\right)$

$1$

$\mathrm{upperbound}\left(\mathrm{ds}\right)$

$3$

$\mathrm{ds}≔\mathrm{DataSeries}\left(\left[\right]\right)$

$\mathrm{ds}≔\left[\begin{array}{}\end{array}\right]$

$\mathrm{numelems}\left(\mathrm{ds}\right)$

$0$

$\mathrm{lowerbound}\left(\mathrm{ds}\right)$

$1$

$\mathrm{upperbound}\left(\mathrm{ds}\right)$

$0$

The DataSeries/numelems, DataSeries/lowerbound and DataSeries/upperbound commands were introduced in Maple 2016.

For more information on Maple 2016 changes, see Updates in Maple 2016.