See https://code.jsoftware.com/wiki/Essays/Extended_Precision_Functions, in particular the Square Root section. On Thu, Nov 1, 2018 at 12:13 PM Skip Cave <skip at caveconsulting.com> wrote: > a=:1234567890101020405060708090x >>> a=2^~a^1r2 >> 1 >> a=2^~%:a >> 1 >> a-:2^~a^1r2 >> 1 >> a-:2^~%:a >> 1 >>> NB. All looking good. However: >>> x:2^~a^1r2 >> 1234567890101024064259751936 >> a >> 1234567890101020405060708090 >>> NB. Clearly not equal. >>> x:2^~%:a >> 1234567890101020490846961664 >> a >> 1234567890101020405060708090 >>> NB. Also clearly not equal, and different from the first one! >>> What's going on! >>> Skip > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm