sub i2dd {
  use Math::MPFR qw(:mpfr);
  my $prec = Rmpfr_get_default_prec();
  Rmpfr_set_default_prec(2098);
  my $val = Math::MPFR->new($_[0]);
  my $hi = Rmpfr_get_d($val, MPFR_RNDN);
  $val -= $hi;
  my $lo = Rmpfr_get_d($val, MPFR_RNDN);

  # Revert to original precision:
  Rmpfr_set_default_prec($prec);

  return($hi, $lo);
}