Meissel–Mertens constant: Difference between revisions
→{{header|Java}}
Line 493:
<syntaxhighlight>
import java.util.ArrayList;
import java.util.BitSet;
import java.util.List;
public final class MeisselMertensConstant {
public static void main(String[] aArgs) {
List<Double> primeReciprocals = listPrimeReciprocals(1_000_000_000);
final double euler = 0.577_215_664_901_532_861;
double sum = 0.0;
for ( double reciprocal : primeReciprocals ) {
sum += reciprocal + Math.log(1.0 - reciprocal);
}
final double constant = euler + sum;
System.out.println("The Meissel-Mertens constant = " + constant);
}
private static List<Double> listPrimeReciprocals(int aLimit) {
BitSet sieve = new BitSet(aLimit + 1);
sieve.set(2, aLimit + 1);
final int squareRoot = (int) Math.sqrt(aLimit);
for ( int i = 2; i <= squareRoot; i = sieve.nextSetBit(i + 1) ) {
for ( int j = i * i; j <= aLimit; j = j + i ) {
sieve.clear(j);
}
}
List<Double> result = new ArrayList<Double>(sieve.cardinality());
for ( int i = 2; i >= 0; i = sieve.nextSetBit(i + 1) ) {
result.add(1.0 / i);
}
return result;
}
}
</syntaxhighlight>
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<pre>
The Meissel-Mertens constant = 0.26149721287104916
</pre>
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