function showimage(A)
% Show the matrix A as a grayscale image.
% Elements should lie between 0 and 1, or will be truncated to
% this range.
k = rank(A);
% restrict elements to interval [0,1]:
A = min(A, 1);
A = max(A, 0);
% Put in as components of RGB map:
% All three components equal ==> gray scale
[m,n] = size(A);
C = zeros(m,n,3);
C(:,:,1) = A;
C(:,:,2) = A;
C(:,:,3) = A;
image(C)
title(sprintf('Rank %i matrix', k))