extend.m

function A = extend(A, c)
%EXTEND Add a rank-1 e * c' correction to A, where e = ones(inf,1).
%
% If the correction has already been set, the new value of C replaces it.

if min(size(A)) ~= inf
    error([ 'extended Toeplitz arithmetic is only supported for ' ...
        'infinite matrices' ]);
end


l = cumsum(abs(c(end:-1:1)));
m = sum(l > norm(c, 1) * cqtoption('threshold'));
c = c(1:m);
A.c = reshape(c, 1, m);

end