what is shs?

[YUYING07]

    flat_grad_grad_kl = torch.cat([grad.contiguous().view(-1) for grad in grads]).data

    return flat_grad_grad_kl + v * damping

stepdir = conjugate_gradients(Fvp, -loss_grad, 10)

shs = 0.5 * (stepdir * Fvp(stepdir)).sum(0, keepdim=True)

lm = torch.sqrt(shs / max_kl)
fullstep = stepdir / lm[0]

According to the TRPO formular,
$direction=\sqrt{(\frac{2\delta}{g^T F^{-1} g})} F^{-1} g$,
So $shs=g^T F^{-1} g$,
but your coding is different from that, why?