function [paddedv, nfront, nback] = padwithzeros(v)
% FUNCTION:    padwithzeros             Part of DPWT Toolbox
%
% SYNOPSIS:    [PADDEDV, NFRONT, NBACK] = padwithzeros(v)
%
% DESCRIPTION: padwithzeros(V) prepends and postpends zeros onto input vector
%              V until its length is an integer power of 2.
%              If the difference between the length of V and 
%              the next highest power of 2 is odd then 
%              ceil((2^p - length(v))/2) zeros are prepended
%              and floor((2^p - length(v))/2) are postpended.
%              If the difference is even then half the missing
%              zeros are added to each end. If V is a column
%              (row) then paddedv is a column(row). NFRONT and NBACK
%              return the number of zeros added to the front and back
%              of V to make PADDEDV, the padded version of V.
%
% EXAMPLE:    v = [1 2 3 4 5];
%            paadwithzerosS(v)
%              ans =
%                0     0     1     2     3     4     5     0
% 
%              To force a vector whose length is already an
%              integer power of 2 to be padded to a length that 
%              is the next power of 2, append a 0 to the vector
%              and then call padwithzeros, e.g. if v is a column
%              (row) vector of length 8 that you wish padded to 
%              length 16 use PADWITHZEROS([v;0]) or if v is a row
%              use PadWithZeros([v,0]).

%
% AUTHOR: Neil Getz
% DATE: 5-14-92 
%
% COPYRIGHT 1992, Neil Getz
%

if (nargin~=1),
  help padwithzeros;
  return;
end;

[m,n] = size(v);
if((m~=1)&(n~=1)),
  error('Arg must be a vector');
end;

lenv = (m>n)*m + (n>=m)*n;

p = ceil(log(lenv)/log(2));
nfront = ceil((2^p - lenv)/2);
nback = 2^p - lenv - nfront;

if(m>n),
  paddedv = [zeros(nfront,1); v; zeros(nback,1)];
else
  paddedv = [zeros(1, nfront), v,  zeros(1,nback)];
end