关于遗忘门的计算：f = 1 - i

[actforjason]

        i, o, g = torch.split(wh_b + wi, split_size_or_sections=self.hidden_size, dim=1)
        i = torch.sigmoid(i)
        g = torch.tanh(g)
        o = torch.sigmoid(o)
        c_num = len(c_input)
        if c_num == 0:
            f = 1 - i
            c_1 = f * c_0 + i * g
            h_1 = o * torch.tanh(c_1)

这里为什么f = 1 - i？