function y = compute_l2ball_projection(x,t)
% compute_l2ball_projection - compute the projection on the l2 ball
%
%   y = compute_l2ball_projection(x,t);
%
%   x is the projection of y on the set {a \ ||a|| <= t }
%

if t<0
    error('t should be > 0');
end
if t==0
    y = x*0;
    return;
end

y = x.*min(1,t/norm(x));