function A = smoke(n, k)
%SMOKE  Complex matrix with a "smoke ring" pseudospectrum.
%   GALLERY('SMOKE',N) is an N-by-N matrix with 1s on the 
%   superdiagonal, 1 in the (N,1) position, and powers of roots of 
%   unity along the diagonal.
%
%   GALLERY('SMOKE',N,1) is the same except for a zero (N,1) element.
%
%   The eigenvalues of GALLERY('SMOKE',N,1) are the N'th roots of unity;
%   those of GALLERY('SMOKE',N) are the N'th roots of unity times 2^(1/N).

%   Reference:
%   [1] L. Reichel and L.N. Trefethen, Eigenvalues and 
%       pseudo-eigenvalues of Toeplitz matrices, Linear Algebra 
%       and Appl., 162-164:153-185, 1992.
%
%   Copyright 1984-2002 The MathWorks, Inc. 
%   $Revision: 1.10 $  $Date: 2002/04/15 03:41:32 $

if nargin < 2, k = 0; end

w = exp(2*pi*i/n);
A = diag( [w.^(1:n-1) 1] ) + diag(ones(n-1,1),1);
if k == 0, A(n,1) = 1; end