window

Compute a window function used for signal windowing in sighnal processing algorithms.

Usage

window(type, x {, scale {, par}})

type

selects the type of the window function (described below); must be number

x

• If x is a scalar, the argument is used as window length and the result of window is a vector containing the window function.
• If x is a vector or matrix, the number of rows of x is used as window length and the result of window is a matrix with the same dimensions as x where each column contains the windowed values of the input column.

The window length must be greater than 2!

scale

A boolean argument to enable/disable energy correction. If the energy correction is enabled, the window function is scaled by a factor that approximately equalises the energy loss caused by the windowing.

lo

lower boundary, must be a number

hi

upper boundary, must be a number

Result

The result r is a copy of x but the values of the elements of r are limited to the boundaries defined by lo and/or hi.

r_i,j is set to lo if x_i,j is lower than lo (functions limit and limitlow)

r_i,j is set to hi if x_i,j is greater than hi (functions limit and limithigh)

See also

vsubc, select

Example:

#a := eval vv(1,2,3,4,5,4,3,2,1)
#b := eval fill(9,0,1)
#c := eval limitlow($#a, 3)
// -> $#c = { 3 , 3 , 3 , 4 , 5 , 4 , 3 , 3 , 3 } 
#d := eval limit($#b, 2, 6)
// -> $#d[*,0] = { 2 , 2 , 3 , 4 , 5 , 4 , 3 , 2 , 2 }
//    $#d[*,1] = { 2 , 2 , 2 , 3 , 4 , 5 , 6 , 6 , 6 }

<function list>

General window function

Usage:	window(type, x, scale, par)
Parameters:
type=0 -> none (square)	type=1 -> whanning
type=2 -> whamming	type=3 -> wblackman
type=4 -> wkaiser	type=5 -> wbartlett
type=6 -> wtaprect	type=7 -> wnuttall
type=8 -> wflattop	type=9 -> wgauss

The arguments x, scale and par are the same as above.

arguments: x The window length (scalar, >2), the signal (vector or matrix, nrow(x)>2). If x is a matrix, every column is multiplied with the window. scale The scaling (0=unscaled, 1=scaled for rms(sig) ~ rms(sig * wnd) par optional window parameters

The result is the signal window of length x or the signal multiplied by the window.