function B = makeposdef(A)
[V,E] = eig(A);
E = diag(E);
ii = find(E>0);
V = V(:,ii);
D = diag(E(ii));
B = V * D * V';
B = (B+B')/2;
B = B + eye(size(B));
return
B = sqrtm(A*A);
B = real(B);
B = (B+B')/2;
%I = eye(size(B));
%B = B + 10*I;
return

f = eps;
I = eye(size(A));
lmin0 = min(eig(A));
while 1
  lmin = min(eig(A+(1+f)*abs(lmin0)*I));
  if lmin < 0
    f = f*2;
  else
    break
  end
end
B = A+(1+f)*abs(lmin0)*I;

return
[V,E] = eig(A);
E = diag(E);
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ii = find(E>0);
V = V(:,ii);
D = diag(E(ii));
B = V * D * V';
B = (B+B')/2;
return

[V,E] = eig(A);
E = diag(E);
E = max(E,eps);
D = diag(E);
B = V * D * V';

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