Arithmetic/Rational: Difference between revisions

=={{header|Java}}==

Uses BigRational class: [[Arithmetic/Rational/Java]]

<lang java>class BigRationalFindPerfectNumbers

{

public static void main(String[] args)

{

int MAX_NUM = (1 << 19);

BigRational TWO = BigRational.valueOf(2);

for (int i = 1; i < MAX_NUM; i++)

{

BigRational reciprocalSum = BigRational.ONE;

if (i > 1)

reciprocalSum = reciprocalSum.add(BigRational.valueOf(i).reciprocal());

int maxDivisor = (int)Math.sqrt(i);

if (maxDivisor >= i)

maxDivisor--;

for (int divisor = 2; divisor <= maxDivisor; divisor++)

{

if ((i % divisor) == 0)

{

reciprocalSum = reciprocalSum.add(BigRational.valueOf(divisor).reciprocal());

int dividend = i / divisor;

if (divisor != dividend)

reciprocalSum = reciprocalSum.add(BigRational.valueOf(dividend).reciprocal());

}

}

if (reciprocalSum.equals(TWO))

System.out.println(String.valueOf(i) + " is a perfect number");

}

return;

}

}

</lang>

Output:

<pre>6 is a perfect number

28 is a perfect number

496 is a perfect number

8128 is a perfect number</pre>