function val=WynnEpsilon(a,steps,object,display)
% function S = WynnEpsilon(a,steps,object,display)
%
% extrapolates a sequence or series by using 
% Wynn's epsilon algorithm
%
% a         vector of terms
% steps     number of extrapolation steps 
%           (method needs 2*steps+1 elements of a)
% object    'sequence': extrapolation to the limit of a
%           'series'  : extrapolation to the limit of cumsum(a)
% display   'on': plot the absolute value of differences in the 
%           first row of the extrapolation table for diagnosis
%
% S         extrapolatd value

% Vektor a als Spaltenvektor anpassen
dims = size(a);
if dims(1) == 1
    a = a';
end

S=zeros(length(a),2*steps+1);
switch object
    case 'sequence'
        S(:,1)=a;
    case 'series'
        S(:,1)=cumsum(a);
    otherwise
        error('MATLAB:badopt','%s: no such object known',object);
end
for j=2:2*steps+1
    if j==2
        switch object
            case 'sequence'
        S(1:end-j+1,j)=1./diff(a);
            case 'series'
        S(1:end-j+1,j)=1./a(2:end); 
        end
    else
       S(1:end-j+1,j)=S(2:end-j+2,j-2)+1./diff(S(1:end-j+2,j-1));
    end
end
S=S(:,1:2:end);
if isequal(display,'on')
    h=semilogy(0:length(S(1,:))-2,abs(diff(S(1,:))));
    set(h,'LineWidth',3);
end
val=S(1,end);
S;
return