choosenfromm.m.txt

这是马尔可夫-蒙特卡罗算法的MATLAB源程序.

function x = ChooseNFromM(m,n)
% x = ChooseNFromM(m,n)
% Choose n distinct members from 1:m, by sampling uniformly at random without replacement

% Colin Fox, 20 Jan 2003

if m<n, disp('Error in ChooseNFromM'), x=[]; return, end

xset = 1:m;
x = zeros(1,n);
for count = 1:n
%    ind = PickOneFromM(length(xset));
%    ind = PickOneFromM(m);
    ind = min(floor(rand*m)+1,m);
    x(count) = xset(ind);
    xset(ind) = []; % zap that element
    m=m-1;
end