A-M baby

Task/Arithmetic-Rational/Icon/arithmetic-rational-1.icon

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+procedure main()
+   limit := 2^19
+
+   write("Perfect numbers up to ",limit," (using rational arithmetic):")
+   every write(is_perfect(c := 2 to limit))
+   write("End of perfect numbers")
+
+   # verify the rest of the implementation
+
+   zero := makerat(0)          # from integer
+   half := makerat(0.5)        # from real
+   qtr  := makerat("1/4")      # from strings ...
+   one  := makerat("1")
+   mone := makerat("-1")
+
+   verifyrat("eqrat",zero,zero)
+   verifyrat("ltrat",zero,half)
+   verifyrat("ltrat",half,zero)
+   verifyrat("gtrat",zero,half)
+   verifyrat("gtrat",half,zero)
+   verifyrat("nerat",zero,half)
+   verifyrat("nerat",zero,zero)
+   verifyrat("absrat",mone,)
+
+end
+
+procedure is_perfect(c)       #: test for perfect numbers using rational arithmetic
+   rsum := rational(1, c, 1)
+   every f := 2 to sqrt(c) do
+      if 0 = c % f then
+         rsum := addrat(rsum,addrat(rational(1,f,1),rational(1,integer(c/f),1)))
+   if rsum.numer = rsum.denom = 1 then
+      return c
+end