'log'   =>      sub { $_[0]->copy()->blog($_[1]); },

##</code><code>##

sub blog
  {
  # not implemented yet
  my ($self,$x,$base,$a,$p,$r) = ref($_[0]) ? (ref($_[0]),@_) : objectify(1,@_);

  return $upgrade->blog($x,$base,$a,$p,$r) if defined $upgrade;

  return $x->bnan();
  }

##</code><code>##

  my ($rc,$exact) = $CALC->_log_int($x->{value},$base->{value});

##</code><code>##

sub _log_int
  {
  # calculate integer log of $x to base $base
  # ref to array, ref to array - return ref to array
  my ($c,$x,$base) = @_;

  # X == 0 => NaN
  return if (scalar @$x == 1 && $x->[0] == 0);
  # BASE 0 or 1 => NaN
  return if (scalar @$base == 1 && $base->[0] < 2);