benchmark.sieve: calculating the number of primes in [1,100,000,000].

extra/benchmark/sieve/sieve.factor

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+USING: bit-arrays kernel locals math math.functions math.ranges
+sequences ;
+IN: benchmark.sieve
+
+:: sieve ( n -- #primes )
+    n dup odd? [ 1 + ] when 2/ <bit-array> :> sieve
+    t 0 sieve set-nth
+
+    3 n sqrt 2 <range> [| i |
+        i 2/ sieve nth [
+            i sq n i 2 * <range> [| j |
+                t j 2/ sieve set-nth
+            ] each
+        ] unless
+    ] each
+
+    sieve [ not ] count 1 + ;
+
+: sieve-benchmark ( -- )
+    100,000,000 sieve 5,761,455 assert= ;
+
+MAIN: sieve-benchmark