Using "array_or_vector"
instead of just "vector"
in a
signature makes an important difference: E.g., if we had
setMethod(crossprod, c(x="mpfr", y="vector"), function(x,y) CPR(x,y))
,
a call crossprod(x, matrix(1:6, 2,3))
would extend into a call
of CPR(x, as(y, "vector"))
such that CPR()
's second
argument would simply be a vector instead of the desired
\(2\times3\) matrix.