function A = cycol(n, k)
%CYCOL  Matrix whose columns repeat cyclically.
%   A = GALLERY('CYCOL',[M N], K) is an M-by-N matrix of the form 
%   A = B(1:M,1:N) where B = [C C C...] and C = RANDN(M, K). Thus A's 
%   columns repeat cyclically, and A has rank at most K. K need not 
%   divide N. K defaults to ROUND(N/4).
%   GALLERY('CYCOL',N,K), where N is a scalar, is the same as 
%   GALLERY('CYCOL',[N N], K).

%   Note:
%   This type of matrix can lead to underflow problems for Gaussian
%   elimination. See the reference below.
%
%   Reference:
%   [1] NA Digest Volume 89, Issue 3 (January 22, 1989).
%
%   Copyright 1984-2002 The MathWorks, Inc. 
%   $Revision: 1.10 $  $Date: 2002/04/15 03:41:26 $

m = n(1);              % Parameter n specifies dimension: m-by-n.
n = n(length(n));

if nargin < 2, k = max(round(n/4),1); end

A = randn(m, k);
for i=2:ceil(n/k)
    A = [A A(:,1:k)];
end

A = A(:, 1:n);