Thanks Jussi. best regards andreas Am Freitag, den 17.04.2009, 01:02 +0300 schrieb Jussi Lahtinen: > Confirmed. > > Regards, > Jussi > > > > ?(Atnh(0.5)) > > 3,162277660168 > > > > but this is wrong. The definition of atanh() should be: