Possible typo in the log_p() function

[univanxx]

Hi there and thanks for an amazing work! I was exploring the code and in the module distributions.py found out that the logarithm of standard normal distribution (normalized_samples in the code) is:

$$ \ln(p) = -0.5 \cdot x^2 - 0.5 \cdot \ln(2 \cdot \pi) - \ln(\sigma). $$

But why do we need a $\ln(\sigma)$ part? Isn't the formula above should look like:

$$ \ln(p) = -0.5 \cdot x^2 - 0.5 \cdot \ln(2 \cdot \pi)? $$

Thanks in advance for the clarifications!