function A=wilk61(n)
%
% function A=wilk61(n)
%  Contrives one of Wilkinson's famous examples of failure for
%  Gaussian elimination with partial pivoting.
%  n=75 will get a matrix where A-L*U is O(1) in MATLAB
%
  A=eye(n)-tril(ones(n,n),-1);
  A(:,n)=ones(n,1);