Harmonic series: Difference between revisions
→{{Header|Java}}
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=={{Header|Java}}==
<syntaxhighlight>
import java.math.BigInteger;
/**
* Java does not have a built-in fraction type, so we create our own class Rational.
*/
public class HarmonicSeries {
public static void main(String[] aArgs) {
System.out.println("The first twenty Harmonic numbers:");
for ( int i = 1; i <= 20; i++ ) {
System.out.println(String.format("%2s", i) + ": " + harmonicNumber(i));
}
System.out.println();
for ( int i = 1; i <= 10; i++ ) {
System.out.print("The first term greater than ");
System.out.println(String.format("%2s%s%5s", i, " is Term ", indexedHarmonic(i)));
}
}
private static Rational harmonicNumber(int aNumber) {
Rational result = Rational.ZERO;
for ( int i = 1; i <= aNumber; i++ ) {
result = result.add( new Rational(BigInteger.ONE, BigInteger.valueOf(i)) );
}
return result;
}
private static int indexedHarmonic(int aTarget) {
BigInteger target = BigInteger.valueOf(aTarget);
Rational harmonic = Rational.ZERO;
BigInteger next = BigInteger.ZERO;
while ( harmonic.numerator.compareTo(target.multiply(harmonic.denominator)) <= 0 ) {
next = next.add(BigInteger.ONE);
harmonic = harmonic.add( new Rational(BigInteger.ONE, next) );
}
return next.intValueExact();
}
private static class Rational {
private Rational(BigInteger aNumerator, BigInteger aDenominator) {
numerator = aNumerator;
denominator = aDenominator;
BigInteger gcd = numerator.gcd(denominator);
numerator = numerator.divide(gcd);
denominator = denominator.divide(gcd);
}
@Override
public String toString() {
return numerator + " / " + denominator;
}
private Rational add(Rational aRational) {
BigInteger numer = numerator.multiply(aRational.denominator).add(aRational.numerator.multiply(denominator));
BigInteger denom = aRational.denominator.multiply(denominator);
return new Rational(numer, denom);
}
private BigInteger numerator;
private BigInteger denominator;
private static final Rational ZERO = new Rational(BigInteger.ZERO, BigInteger.ONE);
}
}
</syntaxhighlight>
=={{header|jq}}==
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