def N0(mean, variance):
    return ((1.0 / tf.sqrt(((2.0 * m.pi) * variance))) * tf.exp(((- (mean ** 2)) / (2 * variance))))
def N0(mean, variance):
    return ((1.0 / tf.sqrt(((2.0 * m.pi) * variance))) * tf.exp(((- (mean ** 2)) / (2 * variance))))