def kl_isotropic_to_standard_gaussian(mean, log_variance):
	"""
	Compute the KL divergence of N(mean, std*I) to N(0, I).
	References:
	Kingma and Willing 2014. Auto-Encoding Variational Bayes.
	"""
	return  - 0.5 * (1 + log_variance - mean.pow(2) - log_variance.exp()).sum()