rvmean computes the means of the simulations of all individual
components of a random vector (rv) object.
E is an alias for rvmean, standing for "Expectation."
Pr is another alias for rvmean, standing for "Probability
of"; suggested to be used when the argument is a logical statement
involving random variables (that is, a description of an event such as
x>0 or x>y). Then Pr(x>0) gives the probability of the
event "x>0". The statement x>0 returns a Bernoulli (indicator)
random variable object (having 1/0 or TRUE/FALSE values) and the expectation
of such variable is just the probability of the event where the indicator is
one.