In reply to Rick Wicklin.

To clarify, my question was whether it should be the unscaled covariance matrix Sigma that is used as input in the statement

TDensity = MVTPDF(xy, DF, mu, Sigma);

Or if it should be df-adjusted first:

TDensity = MVTPDF(xy, DF, mu, Sigma*(df-2)/df);