A Maxima version: (%i1) bigfloatepsilon () := bfloat(2^-?fpprec); Barton -----maxima-bounces at math.utexas.edu wrote: ----- >(%i2) :lisp(defun $bigfloatepsilon () ($bfloat (div 1 (expt 2 fpprec))))); >$BIGFLOATEPSILON >