function [a] = fct(f)

// Output variables initialisation (not found in input variables)
a=[];

// Display mode
mode(0);

// Display warning for floating point exception
ieee(1);

//points x=-cos(pi/N*0:N);

f = f($:-1:1,:);
A = size(mtlb_double(f));N = A(1);

F = mtlb_ifft(mtlb_double([f(1:N,:);f(N-1:-1:2,:)]));
a = [F(1,:);2*F(2:N-1,:);F(N,:)];

a = real(a);
endfunction
