roundMpfr: Rounding to Binary bits, "mpfr-internally"
Description
Rounding to binary bits, not decimal digits. Closer to the number
representation, this also allows to increase or decrease a number's
precBits. In other words, it acts as setPrec(), see
getPrec().
# NOT RUN { (p1 <- Const("pi", 100)) # 100 bit prec roundMpfr(p1, 120) # 20 bits more, but "random noise" Const("pi", 120) # same "precision", but really precise# }