import torch 

def kl_gaussians(mean1, logvar1, mean2, logvar2):
    """ Compute the KL divergence between two gaussians."""
    return 0.5 * (logvar2-logvar1 + torch.exp(logvar1 - logvar2) + torch.pow(mean1 - mean2, 2) * torch.exp(-logvar2)-1.0)