vae_loss_correlated: A custom loss function for a VAE learning a multivariate...
In converseg/ML2Pvae: Variational Autoencoder Models for IRT Parameter Estimation

A custom loss function for a VAE learning a multivariate normal distribution with a full covariance matrix

vae_loss_correlated(
  encoder,
  inv_skill_cov,
  det_skill_cov,
  skill_mean,
  kl_weight,
  rec_dim
)

`encoder`	the encoder model of the VAE, used to obtain z_mean and z_log_cholesky from inputs
`inv_skill_cov`	a constant tensor matrix of the inverse of the covariance matrix being learned
`det_skill_cov`	a constant tensor scalar representing the determinant of the covariance matrix being learned
`skill_mean`	a constant tensor vector representing the means of the latent skills being learned
`kl_weight`	weight for the KL divergence term
`rec_dim`	the number of nodes in the input/output of the VAE