container : rtable, predefined Array for holding results

The DownSample( A, factor, phase ) command down-samples the signal in the Array A.

The effect of this command is to copy one sample from each block of factor samples in A to the output.

Before the code performing the computation runs, Maple converts A to a hardware datatype, first attempting float[8] and subsequently complex[8], unless it already has one of these datatypes. For this reason, it is most efficient if A has one of these datatypes beforehand.

The phase argument determines an offset, so that the sample value from A occurs phase positions offset in the output array. The value of phase must be non-negative and less than the value of factor.

If the container=C option is provided, then the results are put into C and C is returned. With this option, no additional memory is allocated to store the result. The container must be an Array of size iquo( N + factor - 1 - phase, factor ) where N is the number of elements of A, and it must have datatype float[8] if A is real and complex[8] if A is complex.

The SignalProcessing[DownSample] command is thread-safe as of Maple 17.

For more information on thread safety, see index/threadsafe.

$\mathrm{with}\left(\mathrm{SignalProcessing}\right)\:$

$A≔\mathrm{Array}\left(\left[1\,2\,3\,4\,5\,6\,7\,8\,9\right]\,\'\mathrm{datatype}\'\={\'\mathrm{float}\'}_8\right)$

$A≔\left[\begin{array}{ccccccccc}1.& 2.& 3.& 4.& 5.& 6.& 7.& 8.& 9.\end{array}\right]$

$\mathrm{DownSample}\left(A\,1\right)$

$\left[\begin{array}{ccccccccc}1.& 2.& 3.& 4.& 5.& 6.& 7.& 8.& 9.\end{array}\right]$

$\mathrm{DownSample}\left(A\,2\right)$

$\left[\begin{array}{ccccc}1.& 3.& 5.& 7.& 9.\end{array}\right]$

$\mathrm{DownSample}\left(A\,3\right)$

$\left[\begin{array}{ccc}1.& 4.& 7.\end{array}\right]$

$\mathrm{DownSample}\left(A\,4\right)$

$\left[\begin{array}{ccc}1.& 5.& 9.\end{array}\right]$

$\mathrm{DownSample}\left(A\,3\,0\right)$

$\left[\begin{array}{ccc}1.& 4.& 7.\end{array}\right]$

$\mathrm{DownSample}\left(A\,3\,1\right)$

$\left[\begin{array}{ccc}2.& 5.& 8.\end{array}\right]$

$\mathrm{DownSample}\left(A\,3\,2\right)$

$\left[\begin{array}{ccc}3.& 6.& 9.\end{array}\right]$

$C≔\mathrm{Array}\left(1..4\,\'\mathrm{datatype}\'\={\'\mathrm{float}\'}_8\right)\:$

$\mathrm{DownSample}\left(A\,2\,1\,\'\mathrm{container}\'\=C\right)$

$\left[\begin{array}{cccc}2.& 4.& 6.& 8.\end{array}\right]$

$C$

$\left[\begin{array}{cccc}2.& 4.& 6.& 8.\end{array}\right]$

The SignalProcessing[DownSample] command was introduced in Maple 17.

For more information on Maple 17 changes, see Updates in Maple 17.