You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: wmtsa_qmf.m
    path of file: ./repos/bspm/thirdparty/brainwavelet_v1.1_fMRI_OSX/third_party/wmtsa/dwt
    
    the code of the file until where you have to start completion: function [b] = wmtsa_qmf(a, inverse)
% wmtsa_qmf -- Calculate quadrature mirror filter (QMF).
%

    
function [b] = wmtsa_qmf(a, inverse)
% wmtsa_qmf -- Calculate quadrature mirror filter (QMF).
%
%****f* wmtsa.dwt/wmtsa_qmf
%
% NAME
%   wmtsa_qmf -- Calculate quadrature mirror filter (QMF).
%
% USAGE
%   [b] = function_name(a, [inverse])
%
% INPUTS
%   * a           -- filter coefficients (vector).
%   * inverse     -- (optional) flag for calculating inverse QMF (Boolean).
%                    Default: inverse = 0 (FALSE).
%
% OUTPUTS
%    b            - QMF coefficients (vector).
%
% SIDE EFFECTS
%
%
% DESCRIPTION
%    wmtsa_qmf calculates the quadrature mirror filter (QMF) of
%    for the specified filter coefficients.  If a is a vector,
%    the QMF of the vector is calculated.  If a is a matrix or higher
%    order array, the QMF is calculated along the first dimension.
%
%   The inverse flag, if set, calculates the inverse QMF.  inverse
%   is a Boolean values specified as (1/0, y/n, T/F or true/false).
%
% EXAMPLE
%    % h is the QMF of g.
%    g = [0.7071067811865475 0.7071067811865475];
%    h = wmtsa_qmf(g);
%
%    % g is the inverse QMF of h.
%    h = [0.7071067811865475 -0.7071067811865475];
%    g = wmtsa_qmf(h, 1);
%
% ALGORITHM
%      g_l = (-1)^(l+1) * h_L-1-l
%      h_l = (-1)^l * g_L-1-l
%    See pages 75 of WMTSA for additional details.
%
% REFERENCES
%   Percival, D. B. and A. T. Walden (2000) Wavelet Methods for
%   Time Series Analysis. Cambridge: Cambridge University Press.
%
% SEE ALSO
%   yn
%
% TOOLBOX
%   wmtsa/dwt
%
% CATEGORY
%   Filters:  Utilities
%

% AUTHOR
%   Charlie Cornish
%
% CREATION DATE
%   2005-02-02
%
% COPYRIGHT
%   (c) 2005  Charles R. Cornish
%
% CREDITS
%
%
% REVISION
%   $Revision: 612 $
%
%***

%   $Id: wmtsa_qmf.m 612 2005-10-28 21:42:24Z ccornish $

usage_str = ['Usage:  [b] = ', mfilename, ...
             '(a, [inverse])'];


error(nargerr(mfilename, nargin, [1:2], nargout, [0:1], 1, usage_str, 'struct'));

if (~exist('inverse', 'var') || isempty(inverse))
  inverse = 0;
end