rvvar computes the means of the simulations of all individual
components of a random vector (rv) object.
That is, rvvar applies the function var to the vector of
simulations of each component of x, thus computing "columnwise"
variances of the matrix of simulations of x.
rvsd applies the function sd to the vector of simulations of
each component of x, thus computing "columnwise" standard deviations
of the matrix of simulations of x.