makewindow.sci

来自「小波分解源代码」· SCI 代码 · 共 47 行

function win=MakeWindow(Name,n)
// MakeWindow -- Make artificial Window
//  Usage
//    wig = MakeWindow(Name,n)
//  Inputs
//    Name   string: 'Rectangle', 'Hanning', 'Hamming',
//            'Gaussian', 'Blackman';
//    n      desired half Window length
//  Outputs
//    win    1-d Window, with length 2n+1;
//  Description
//    Rectangle		1
//    Hanning 		cos(pi*t)^2
//    Hamming		.54 + .46cos(2pi*t)
//    Gaussian		exp(-18 * t^2/2)
//    Blackman		.42 + .50*cos(2pi*t) + .08cos(4.*pi.*t)
//  Examples
//     win = MakeWindow('Rectangle',17);	plot(win);
//     win = MakeWindow('Hanning',  17);	plot(win);
//     win = MakeWindow('Hamming',  17);	plot(win);
//     win = MakeWindow('Gaussian', 17);	plot(win); 
//     win = MakeWindow('Blackman', 17);	plot(win);
//  See Also
//
//  Algorithm
//    Easy to implement.
//  References
//    Mallat, "A Wavelet Tour of Signal Processing"; 4.2.2 Choice of Window.
//
//  Copyright Aldo I Maalouf

 t = ((1:(2*n+1))-(n+1))./n./2;

 if string(Name)=='Rectangle',
        tt=size(t);
 	win = ones(tt(1),tt(2));
 elseif string(Name)=='Hanning',
	win = realpow(cos(%pi.*t),2);
 elseif string(Name)=='Hamming',
	win = .54 + .46*cos(2.*pi.*t);
 elseif string(Name)=='Gaussian',
	win = exp(-realpow(t,2)*18);
 elseif string(Name)=='Blackman',
	win = .42 + .50*cos(2.*%pi.*t) + .08*cos(4.*%pi.*t);
 end;
endfunction