function modw = removelevel(w,levels)
% FUNCTION:    removelevel	Part of DPWT Toolbox
%
% USAGE:       MODW = removelevel(W,LEVELS)
%
% DESCRIPTION: Make wavelet coefficients zero at levels 
%              in vector levels. LEVELS must contain integers 
%              greater than or equal to -1 and less than or 
%              equal to the base 2 log of the length of W. A 
%              level of -1 refers to the first coefficient in
%              W.
%
% EXAMPLE:     removelevel([1  2  3 4  5 6 7 8], [0 2])
%              ans =
%                  1     0     3     4     0     0     0     0
%

%
% AUTHOR: Neil Getz
% DATE: 2-12-92
%
% COPYRIGHT 1992, Neil Getz
%
if (nargin ~= 2),
  help removelevel;
  return;
end
n = length(w);
pp = log(n)/log(2);
if( (levels<pp) & (levels>=-1) & (levels == round(levels)) ),
else
  s = ['arg2 must be integer and', ...
       '-1< = arg2 < log2(length( arg1))'];
  error(s);
end;
modw = w;
if (sum( levels == -1 ) >= 1), 
  modw(1)=0; 
end;
for res = levels( find( levels > -1 ) )
  modw([(2^res + 1):(2^(res+1))]) = zeros(2^res,1);
end