A vector of the same length as the longest of x,q, ...,
of class mpfr with the high accuracy results of
the corresponding standard R function.
Details
pnorm() is based on erf() and erfc() which
have direct MPFR counter parts and are both reparametrizations
of pnorm, erf(x) = 2*pnorm(sqrt(2)*x) and
erfc(x) = 2* pnorm(sqrt(2)*x, lower=FALSE).