function [hJ, gJ, LJ] = dwt_equivalent_filter(wtfname, J)% dwt_equivalent_filter -- Calculate DWT equivalent filter for J levels.%%****f* wmtsa.dwt/dwt_equivalent_filter%% NAME%   dwt_equivalent_filter -- Calculate DWT equivalent filter for J levels.%% SYNOPSIS%   [hJ, gJ, LJ] = dwt_equivalent_filter(wtfname, J)%% INPUTS%   wtfname      = string containing name of a WMTSA-supported wavelet filter,%                  case-insensitve.%   J            = number of levels (integer > 0)%% OUTPUTS%   hJ           = 1xJ numeric cell array containing equivalent wavelet%                  filter coefficients.%   gJ           = 1xJ numeric cell array containing equivalent scaling%                  filter coefficients.%   LJ           = 1xJ numeric cell array containing widths of the%                  equivalent filters (L_j).%% SIDE EFFECTS%%% DESCRIPTION%%% EXAMPLE%%% WARNINGS%%% ERRORS%%% NOTES%%% BUGS%%% TODO%%% ALGORITHM%%% REFERENCES%%% SEE ALSO%%% AUTHOR%   Charlie Cornish%% CREATION DATE%   2004-01-27%%% COPYRIGHT%%% CREDITS%%% REVISION%   $Revision: 612 $%%***%   $Id: dwt_equivalent_filter.m 612 2005-10-28 21:42:24Z ccornish $  usage_str = ['Usage:  [hJ, gJ, LJ] = ', mfilename, ...               '(wtfname, J)'];  %%  Check input arguments and set defaults.  error(nargerr(mfilename, nargin, [2:2], nargout, [0:3], 1, usage_str, 'struct'));    % Check for valid wavelet and get wavelet filter coefficients  try    wtf_s = dwt_filter(wtfname);  catch    rethrow(lasterror);  end  h = wtf_s.h;  g = wtf_s.g;  L = wtf_s.L;  error(argterr(mfilename, J, 'posint', [], 1, '', 'struct'));  LJ = {};  hJ = {};  gJ = {};  Lj = equivalent_filter_width(L, 1);  LJ{1} = Lj;  hJ{1} = h;  gJ{1} = g;      for (j = 2:J)    Lj = equivalent_filter_width(L, j);    LJ{j} = Lj;    num_zeros = 2^(j-1) - 1;    hj = zeros(1, L+(L-1)*num_zeros);    gj = zeros(1, L+(L-1)*num_zeros);        for (l = 1:L)      ll = (l-1) * num_zeros + l;      hj(ll) = h(l);      gj(ll) = g(l);    end      hJ{j} = conv(gJ{j-1}, hj);    gJ{j} = conv(gJ{j-1}, gj);      end      return