function vc = blkM2vc(M, blkS)
%blkM2vc  Reshaping of a block-matrix into a matrix of vectors
%
% The matrix  M  consists of blocks of size blkS = [r c]
% Each  r by c  block of the matrix  M  is converted into
% a  rc by 1 vector and placed as a column of the matrix  vc

[rr cc] = size(M) ;
r = blkS(1) ; c = blkS(2) ;

if  (rem(rr, r) ~= 0) | (rem(cc, c) ~= 0)
  error('blocks do not fit into matrix')
end

nr = rr/r ; nc = cc/c ; rc = r*c ;
vc = zeros(rc, nr*nc);

for ii = 0:nr-1
   vc(:, (1:nc)+ii*nc) = reshape(M((1:r)+ii*r, :), rc, nc) ;
end