!-------------------------------------------
! derived from my book "PROGRAMMARE IN ERRE"
! iterative solution
!-------------------------------------------

PROGRAM FIBONACCI

!$DOUBLE

!VAR F1#,F2#,TEMP#,COUNT%,N%

BEGIN    !main
   INPUT("Number",N%)
   F1=0
   F2=1
   REPEAT
      TEMP=F2
      F2=F1+F2
      F1=TEMP
      COUNT%=COUNT%+1
   UNTIL COUNT%=N%
   PRINT("FIB(";N%;")=";F2)

   ! Obviously a FOR loop or a WHILE loop can
   ! be used to solve this problem

END PROGRAM