function Ht = modwt_wavelet_transfer_function(f, wtfname, j)% modwt_wavelet_transfer_function -- Calculate transfer function for specified MODWT wavelet filter.%%****f* wmtsa.dwt/modwt_wavelet_transfer_function%% NAME%   modwt_wavelet_transfer_function -- Calculate transfer function for%     frequencies f for specified MODWT wavelet filter and (optionally) jth level.%% SYNOPSIS%   Ht_j = modwt_wavelet_transfer_function(f, wtfname, [j])%% INPUTS%   f            - vector of sinsuoidal frequency.%   wtfname      - name of a WMSTA-supported MODWT scaling filter.%   j            - (optional) level (index) of scale.%% OUTPUTS%   Ht           - vector of the transfer function values for MODWT wavelet filter h%                  at frequencies f.%   Ht_j         - vector of the transfer function values for MODWT wavelet filter h%                  at frequencies f at jth level.%% SIDE EFFECTS%%% DESCRIPTION%%% EXAMPLE%%% NOTES%%% ALGORITHM%   See page 163 of WMTSA for Ht.%   See page 169 of WMTSA for Ht_j.%% REFERENCES%   Percival, D. B. and A. T. Walden (2000) Wavelet Methods for%     Time Series Analysis. Cambridge: Cambridge University Press.%% SEE ALSO%%% AUTHOR%   Charlie Cornish%% CREATION DATE%   2003-10-08%% COPYRIGHT%%% REVISION%   $Revision: 612 $%%***% $Id: modwt_wavelet_transfer_function.m 612 2005-10-28 21:42:24Z ccornish $    usage_str = ['Usage:  [Ht] = ', mfilename, ...               '(f, wtfname, [j])'];    %%  Check input arguments and set defaults.  error(nargerr(mfilename, nargin, [2:3], nargout, [0:1], 1, usage_str, 'struct'));    if (nargin > 2)    error(argterr(mfilename, j, 'posint', [], 1, '', 'struct'));  end    if (exist('j', 'var'))    Ht = wavelet_transfer_function_j(f, wtfname, j);  else    Ht = wavelet_transfer_function(f, wtfname);  end  return% Subfunction to calculate MODWT wavelet transfer function.function Ht = wavelet_transfer_function(f, wtfname)  wtf_s = modwt_filter(wtfname);  ht = wtf_s.h;  gt = wtf_s.g;  L = wtf_s.L;  the_sum = 0;  for (l = 0:L-1)    htl = ht(l+1);    the_sum = the_sum + htl * exp( -i * 2 * pi * f * l);  end  Ht = the_sum;  return% Subfunction to calculate MODWT wavelet transfer function for jth level.function Ht_j = wavelet_transfer_function_j(f, wtfname, j)  Ht = wavelet_transfer_function(2^(j-1) * f, wtfname);  the_product = 1;  for (l = 0:j-2)    Gt = modwt_scaling_transfer_function(2^l * f, wtfname);    the_product = the_product .* Gt;  end  Ht_j = Ht .* the_product;  return