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Prolog Source  |  1987-10-21  |  294 b   |  20 lines
  1. /* FACT1.PRO */
  2.  
  3. /* Recursive program to compute factorials.
  4.    This is not tail recursive. */
  5.  
  6. PREDICATES
  7.  
  8.   factorial(integer,real)
  9.  
  10. CLAUSES
  11.  
  12.   factorial(1,1).
  13.  
  14.   factorial(X,FactX) :-
  15.         X > 1,
  16.         Y = X-1,
  17.         factorial(Y,FactY),
  18.         FactX = X*FactY.
  19.  
  20.