440 "," CLEAR : INPUT "a=";A#,"b=";B#,"step=";N: CLS :N= INT (N/2)*2
  441 Y=0:H#=0:O#=0:P#=0:S#= ABS ((B#-A#)/2/N):X#=A#: GOSUB 1:H#=F#
  442 X#=X#+S#: GOSUB 1:O#=O#+F#: IF Y=N-1 THEN 444
  443 X#=X#+S#: GOSUB 1:P#=P#+F#:Y=Y+1: GOTO 442
  444 X#=B#: GOSUB 1:U#=F#:Q#=S#/3*(H#+4*O#+2*P#+U#): PRINT "J="; ABS Q#
  445 IF Z>=2 THEN 447
  446 T#=Q#:N=N/2:Z=2: GOTO 441
  447 R#=(T#-Q#)/15: PRINT "Rs=";R#: PRINT "S(2n)+Rs=";T#+R#: END