function f = block(v, N, M)

% This function separates the vector
% into blocks.  Each block has size N.
% and consecutive blocks differ in
% their starting positions by M
%
% Typically
%   N = 30 msec (600 samples)
%   M = 10 msec (200 samples)

n = length(v);
maxblockstart = n - N + 1;
lastblockstart = maxblockstart - mod(maxblockstart-1 , M);

% Remove the semicolon to see the number of blocks
% numblocks = (lastblockstart-1)/M + 1
numblocks = (lastblockstart-1)/M + 1;

f = zeros(numblocks,N);

for i = 1:numblocks
  for j = 1:N
    f(i,j) = v((i-1)*M+j);
  end
end