vb_lowpass_init

 Exponential dump lowpass filter coefficient
   [a,z] = vb_lowpass_init(fs,Fc)
 --- Input
 fs : Sampling frequencies (Hz)
 Fc : Center frequencies (Hz) for lowpass filter bank   [1 x Nbank]
 D  : Dimension of input signal
 --- Output
 a  : Coefficient of lowpass filter bank                [D x Nbank]
 z  : Internal state variable for lowpass online-filter [D x Nbank]
    = zeros(D,Nbank)

 2007-9-21 Masa-aki Sato

 Copyright (C) 2011, ATR All Rights Reserved.
 License : New BSD License(see VBMEG_LICENSE.txt)

0001 function    [a,z] = vb_lowpass_init(fs,Fc,D)
0002 % Exponential dump lowpass filter coefficient
0003 %   [a,z] = vb_lowpass_init(fs,Fc)
0004 % --- Input
0005 % fs : Sampling frequencies (Hz)
0006 % Fc : Center frequencies (Hz) for lowpass filter bank   [1 x Nbank]
0007 % D  : Dimension of input signal
0008 % --- Output
0009 % a  : Coefficient of lowpass filter bank                [D x Nbank]
0010 % z  : Internal state variable for lowpass online-filter [D x Nbank]
0011 %    = zeros(D,Nbank)
0012 %
0013 % 2007-9-21 Masa-aki Sato
0014 %
0015 % Copyright (C) 2011, ATR All Rights Reserved.
0016 % License : New BSD License(see VBMEG_LICENSE.txt)
0017 
0018 Fc = Fc(:)';
0019 
0020 % Lowpass coefficient
0021 a = exp(-(2*pi)*(Fc/fs));
0022 a = repmat( a, [D 1]);
0023 
0024 z = zeros(size(a));