nonlinearity.py 文件源码

def logaddexp(x1: T.FloatTensor, x2: T.FloatTensor) -> T.FloatTensor:
    """
    Elementwise logaddexp function: log(exp(x1) + exp(x2))

    Args:
        x1: A tensor.
        x2: A tensor.

    Returns:
        tensor: Elementwise logaddexp.

    """
    # log(exp(x1) + exp(x2))
    # = log( exp(x1) (1 + exp(x2 - x1))) = x1 + log(1 + exp(x2 - x1))
    # = log( exp(x2) (exp(x1 - x2) + 1)) = x2 + log(1 + exp(x1 - x2))
    diff = torch.min(x2 - x1, x1 - x2)
    return torch.max(x1, x2) + torch.log1p(exp(diff))