: sqrt
i mark2 dup
i loc0 sto
c /2
i loc1 sto
% loop
i loc0 lod
i loc1 lod
c newton
i dup loc1
c replace!
c thresh
c close?
b loop
i loc1 lod
i ret2

: newton
c tuck
c square
i add div
c /2
i ret0

: square
i dup mul
i ret0
: tuck
i dup nrt
i ret0 

: replace!
i dup lod
i nrt sto
i ret0

: close?
i nrt
c absdiff
i swp sle
i ret0

: /2
i lit2 div
i ret0

: thresh
i lit4 ret0

: absdiff
i sub 

: abs
i lit0 slt
b f1
i neg
% f1
i ret0


: hypot
c square
i swp
c square
i add 
c sqrt
i ret0