I want to implement this function: x / ( 1 - e^(-x )). However, after I’ve done that, all of my loss became nan. I don’t know what happen to me 
and here is my code:
class MyAttn(nn.Module):
    def __init__(self, channel, reduction=16):
        super(MyAttn, self).__init__()
        self.avg_pool = nn.AdaptiveAvgPool2d(1)
        self.fc = nn.Sequential(
            spectral_norm(nn.Linear(channel, channel // reduction, bias=False)),
            nn.ReLU(inplace=True),
            spectral_norm(nn.Linear(channel // reduction, channel, bias=False)),
        )

    def forward(self,  x):
        b, c, _, _ = x.size()
        y = self.avg_pool(x).view(b, c)
        y = self.fc(y)
        
        energy = y / (1  - torch.exp(-y))
        energy = energy.view(b, c, 1, 1)
        return x * energy.expand_as(x)