: epsilon  1.0e-12 ;

with: n

: iter  \ n1 n2 -- n1 n2
    2dup * sqrt >r + 2 / r> ;

: agn  \ n1 n2 -- n
    repeat  iter  2dup epsilon ~= not while!  drop ;

"agn(1, 1/sqrt(2)) = " .  1  1 2 sqrt /  agn  "%.10f" s:strfmt . cr

;with
bye