covDataAccess: Differentially Private Covariance Data Access Function
Description
This function performs the data access step in the computation of a
differentially private covariance. The true values are computed using
cov, while the sensitivities are calculated based on
bounded and unbounded differential privacy Kifer2011DPpack
according to the theoretical values Liu2019bDPpack. For the
covariance, the sensitivities based on bounded and unbounded differential
privacy are identical, so only one value is returned.