function vector=haar_inv(coef)
% Haar inverse transform
%
% Syntax VECTOR=HARR_INV(COEF)
% This function returns the inverse Haar wavelet transform of the
% data in COEF.  The number of elements in COEF must be a power of two.
% VECTOR has length equal to a power of two.
%
% Written by Eric Tittley (940901) etittley@phobos.astro.uwo.ca
%
% See also HAAR
if nargin<1 error('Too few arguments passed to haar'); end
if nargin>1 error('Too many arguments passed to haar'); end
n=length(coef);

k=0;
while(n>2^k) k=k+1; end
pow=k;
if(n~=2^k) error('Length of COEF must be a power of 2 in call to HAAR_INV'); end

coef=coef(:);

vector=coef;
for k=1:pow
 avg=vector(1:2^(k-1));
 diff=vector(2^(k-1)+1:2^k);
 for l=1:2^(k-1)
  vector(2*l-1)=avg(l)+diff(l);
  vector(2*l)=avg(l)-diff(l);
 end
end