Initial data commit

Task/Long-primes/XBasic/long-primes.basic

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+PROGRAM "longprimes"
+VERSION "0.0002"
+
+DECLARE FUNCTION Entry()
+INTERNAL FUNCTION Sieve(limit&, primes&[], count%)
+INTERNAL FUNCTION FindPeriod(n&)
+
+FUNCTION Entry()
+  DIM numbers&[7]
+  numbers&[0] = 500
+  numbers&[1] = 1000
+  numbers&[2] = 2000
+  numbers&[3] = 4000
+  numbers&[4] = 8000
+  numbers&[5] = 16000
+  numbers&[6] = 32000
+  numbers&[7] = 64000
+  numberUpperBound% = UBOUND(numbers&[])
+  DIM totals%[numberUpperBound%]
+  DIM primes&[6499]
+  PRINT "Please wait."
+  PRINT
+  Sieve(64000, @primes&[], @primeCount%)
+  DIM longPrimes&[primeCount% - 1] ' Surely longCount% < primeCount%
+  longCount% = 0
+  FOR i% = 0 TO primeCount% - 1
+    prime& = primes&[i%]
+    IF FindPeriod(prime&) = prime& - 1 THEN
+      longPrimes&[longCount%] = prime&
+      INC longCount%
+    END IF
+  NEXT i%
+  count% = 0
+  index% = 0
+  FOR i% = 0 TO longCount% - 1
+    IF longPrimes&[i%] > numbers&[index%] THEN
+      totals%[index%] = count%
+      INC index%
+    END IF
+    INC count%
+  NEXT i%
+  totals%[numberUpperBound%] = count%
+  PRINT "The long primes up to"; numbers&[0]; " are:"
+  PRINT "[";
+  FOR i% = 0 TO totals%[0] - 2
+    PRINT STRING$(longPrimes&[i%]); " ";
+  NEXT i%
+  IF totals%[0] > 0 THEN
+    PRINT STRING$(longPrimes&[totals%[0] - 1]);
+  END IF
+  PRINT "]"
+  PRINT
+  PRINT "The number of long primes up to:"
+  FOR i% = 0 TO numberUpperBound%
+    PRINT FORMAT$("  #####", numbers&[i%]); " is"; totals%[i%]
+  NEXT i%
+END FUNCTION
+
+FUNCTION Sieve(limit&, primes&[], count%)
+  DIM c@[limit&]
+  FOR i& = 0 TO limit&
+    c@[i&] = 0
+  NEXT i&
+  ' No need to process even numbers
+  p% = 3
+  n% = 0
+  p2& = p% * p%
+  DO WHILE p2& <= limit&
+    FOR i& = p2& TO limit& STEP 2 * p%
+      c@[i&] = 1
+    NEXT i&
+    DO
+      p% = p% + 2
+    LOOP UNTIL !c@[p%]
+    p2& = p% * p%
+  LOOP
+  FOR i& = 3 TO limit& STEP 2
+    IFZ c@[i&] THEN
+      primes&[n%] = i&
+      INC n%
+    END IF
+  NEXT i&
+  count% = n%
+END FUNCTION
+
+' Finds the period of the reciprocal of n&
+FUNCTION FindPeriod(n&)
+  r& = 1
+  period& = 0
+  FOR i& = 1 TO n& + 1
+    r& = (10 * r&) MOD n&
+  NEXT i&
+  rr& = r&
+  DO
+    r& = (10 * r&) MOD n&
+    INC period&
+  LOOP UNTIL r& = rr&
+END FUNCTION period&
+
+END PROGRAM