Blame Examples/twins.b

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/* An example that finds all primes between 2 and limit. */
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define primes (limit) {
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    auto num, p, root, i
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    prime[1] = 2;
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    prime[2] = 3;
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    num = 2;
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    scale = 0;
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    for ( p=5; p <= limit; p += 2)  {
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	root = sqrt(p);
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	isprime = 1;
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	for ( i = 1;  i < num && prime[i] <= root; i++ ) {
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	    if ( p % prime[i] == 0 ) {
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		isprime = 0;
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		break;
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            }
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	}
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	if (isprime) {
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	    num += 1;
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	    prime [num] = p;
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	}
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     }
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}
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print "\ntyping 'twins (10)' will print all twin primes less than 10.\n"
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define twins (limit) {
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   auto i;
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   i = primes(limit+2);
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   for (i=1; prime[i] > 0; i++) {
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      if ((prime[i]+2) == prime[i+1]) \
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	print "twins are ", prime[i], " and ", prime[i+1], "\n"
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   }
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}