function G = chromhpf(F,alpha)
% G = chromhpf(F,alpha)  high-pass filter a chroma matrix
%    F is a chroma matrix (12 rows x N time steps)
%    Apply a one-pole, one-zero high pass filter to each 
%    row, with a pole at alpha (0..1, default 0.99)
% 2007-06-17 Dan Ellis dpwe@ee.columbia.edu
% $Header: $

if nargin < 2;  alpha = 0.9; end

[nr,nc] = size(F);

G = zeros(nr,nc);

for i = 1:nr
  G(i,:) = filter([1 -1], [1 -alpha], F(i,:));
end