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Re: Square Root Of java.math.BigInteger

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JDK 9 has now Hacker sqrt():

The closed: JDK-8032027 : Add BigInteger square root methods
https://bugs.java.com/view_bug.do?bug_id=8032027

In the bug there is a mention of Zimmerman, but Hacker is in OpenJDK:
     * @implNote The implementation is based on the material in Henry S. Warren,
     * Jr., <i>Hacker's Delight (2nd ed.)</i> (Addison Wesley, 2013), 279-282.
https://github.com/netroby/jdk9-dev/blob/master/jdk/src/java.base/share/classes/java/math/MutableBigInteger.java#L1883

Am Sonntag, 25. Mai 2008 05:46:53 UTC+2 schrieb Arne Vajhøj:
> j1mb0jay wrote:
> > Posted the wring code, the code is below LOL !!!!
> > 
> > -------------Square Root Code --------------------
> > 
> > package math;
> > 
> > import java.math.BigInteger;
> > 
> > public class SquareRoot 
> > {
> > 	public static BigInteger squareRoot(BigInteger testSubject, 
> > boolean round)
> > 	{
> 
> My suggestion:
> 
>      private final static BigInteger one = new BigInteger("1");
>      private final static BigInteger two = new BigInteger("2");
>      public static BigInteger sqrt(BigInteger v) {
>          int n = v.toByteArray().length;
>          byte[] b = new byte[n/2+1];
>          b[0] = 1;
>          BigInteger guess = new BigInteger(b);
>          while(true) {
>              BigInteger guessadd1 = guess.add(one);
>              BigInteger guesssub1 = guess.subtract(one);
>              if(guess.multiply(guess).compareTo(v) > 0) {
>                  if(guesssub1.multiply(guesssub1).compareTo(v) <= 0) {
>                      return guesssub1;
>                  }
>              } else {
>                  if(guessadd1.multiply(guessadd1).compareTo(v) > 0) {
>                      return guess;
>                  }
>              }
>              guess = guess.add(v.divide(guess)).divide(two);
>          }
>      }
> 
> Arne

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Re: Square Root Of java.math.BigInteger bursejan@gmail.com - 2018-07-10 04:26 -0700
  Re: Square Root Of java.math.BigInteger bursejan@gmail.com - 2018-07-12 04:38 -0700
    Re: Square Root Of java.math.BigInteger j4n bur53 <janburse@fastmail.fm> - 2018-07-12 15:12 +0200

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