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SignalProcessing

 HammingWindow
 multiply an array of samples by a Hamming windowing function

 Calling Sequence HammingWindow(A)

Parameters

 A - Array of real or complex numeric values; the signal

Options

 • container : Array, predefined Array for holding results
 • inplace : truefalse, specifies that output should overwrite input

Description

 • The HammingWindow(A) command multiplies the Array A by a Hamming windowing function and returns the result in an Array having the same length. The length of A must be at least $3$.
 • The Hamming windowing function $w$ is defined as follows for a sample with $N$ points.

$w\left(k\right)=0.54-0.46\mathrm{cos}\left(\frac{2\mathrm{\pi }k}{N-1}\right)$

 • For an Array with complex values, the real and imaginary parts are multiplied by the same windowing function.
 • Before the code performing the computation runs, A is converted to datatype float or complex if it does not have one of those datatypes already. For this reason, it is most efficient if A has one of these datatypes beforehand. This does not apply if inplace is true.
 • 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 the same size and datatype as A.
 • If the inplace or inplace=true option is provided, then A is overwritten with the results. In this case, the container option is ignored.

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

Examples

 > $\mathrm{with}\left(\mathrm{SignalProcessing}\right):$
 > $a≔\mathrm{GenerateUniform}\left(10,-1,1\right)$
 $\left[\begin{array}{cccccccccc}-0.7852184921503079& 0.5884139649569997& -0.9931658226996676& 0.9215782885439708& -0.03878017095848924& 0.013605792541056892& -0.21075697289779816& 0.7496002158150088& 0.13896635780110977& 0.21228513401001725\end{array}\right]$ (1)
 > $\mathrm{HammingWindow}\left(a\right)$
 $\left[\begin{array}{cccccccccc}-0.06281747937202464& 0.11039796694667911& -0.4569772840506981& 0.7096152821788576& -0.037704354939538026& 0.013228348883527275& -0.1622828691313046& 0.34490742927079837& 0.026072806372548343& 0.016982810720801385\end{array}\right]$ (2)
 > $c≔\mathrm{Array}\left(1..10,'\mathrm{datatype}'={'\mathrm{float}'}_{8},'\mathrm{order}'='\mathrm{C_order}'\right):$
 > $\mathrm{HammingWindow}\left(a,'\mathrm{container}'=c\right)$
 $\left[\begin{array}{cccccccccc}-0.06281747937202464& 0.11039796694667911& -0.4569772840506981& 0.7096152821788576& -0.037704354939538026& 0.013228348883527275& -0.1622828691313046& 0.34490742927079837& 0.026072806372548343& 0.016982810720801385\end{array}\right]$ (3)
 > $c$
 $\left[\begin{array}{cccccccccc}-0.06281747937202464& 0.11039796694667911& -0.4569772840506981& 0.7096152821788576& -0.037704354939538026& 0.013228348883527275& -0.1622828691313046& 0.34490742927079837& 0.026072806372548343& 0.016982810720801385\end{array}\right]$ (4)
 > $a≔\mathrm{GenerateTone}\left(100,1,\frac{1}{\mathrm{Pi}},\mathrm{Pi}\right):$
 > $\mathbf{use}\phantom{\rule[-0.0ex]{0.5em}{0.0ex}}\mathrm{plots}\phantom{\rule[-0.0ex]{0.5em}{0.0ex}}\mathbf{in}\phantom{\rule[-0.0ex]{0.5em}{0.0ex}}\mathrm{display}\left(\mathrm{Array}\left(\left[\mathrm{listplot}\left(a\right),\mathrm{listplot}\left(\mathrm{HammingWindow}\left(a\right)\right)\right]\right)\right)\phantom{\rule[-0.0ex]{0.5em}{0.0ex}}\mathbf{end use}$  > 

Compatibility

 • The SignalProcessing[HammingWindow] command was introduced in Maple 17.