bsplinecurve bscurv  3 2  -1.0 4   1.0 4  0 0 0 1   1 0 0 1   2 0 0 1   3 0 0 1
incdeg bscurv 11
translate bscurv 0 -4 0
set i 1
repeat 100 {cmovepoint bscurv 0 0. 0.05  0.0  ; incr i 1; repaint}
set i 1
repeat 100 {cmovepoint bscurv 0 0. -0.05  0.0 ; incr i 1; repaint}
renamevar bscurv result
checklength result -l 3.0000000000000004