100 cls
110 for i = 0 to 20 : print fibor(i); : next i
120 print
130 for i = 0 to 20 : print fiboi(i); : next i
140 print
150 for i = 0 to 20 : print fiboa(i); : next i
160 end
170 sub fibor(n) : 'Recursive
180   if n < 2 then
190     fibor = n
200   else
210     fibor = fibor(n-1)+fibor(n-2)
220   endif
230 end sub
240 sub fiboi(n) : 'Iterative
250   n1 = 0
260   n2 = 1
270   for k = 1 to abs(n)
280     sum = n1+n2
290     n1 = n2
300     n2 = sum
310   next k
320   if n < 0 then
330     fiboi = n1*((-1)^((-n)+1))
340   else
350     fiboi = n1
360   endif
370 end sub
380 sub fiboa(n) : 'Analytic
390   fiboa = int(0.5+(((sqr 5+1)/2)^n)/sqr 5)
400 end sub