Review Request: BigInteger patch for efficient multiplication and division (#4837946)

[Brian Burkhalter]

Hi Tim,

On Mar 10, 2013, at 1:39 PM, Tim Buktu wrote:

> I have updated the patch. It now contains Alan Eliasen's fast square()
> and pow() implementations.
> Special characters have been replaced with ASCII ones.
> 
> Also included is a patched MutableBigInteger which uses the fast
> division algorithm in BigInteger, and a patched BigDecimal which uses
> the fast BigInteger.pow() method. Both changes speed up BigDecimal division.
> BigDecimal division is still much slower than BigInteger division
> (except BigDecimal.divideAndRound) because it calls doRound(),
> setScale(), and bigMultiplyPowerTen() which are pretty slow. Maybe these
> methods can be made more efficient.
> 
> To view the four patched files (#4 is BigIntegerTest.java) on one page,
> go to
> 
> https://gist.github.com/tbuktu/1576025 ,
> 
> or get them individually at
> 
> https://gist.github.com/tbuktu/1576025/raw/96e9dfd9261862223aa9ff81618f1d85045e85a5/BigInteger.java
> https://gist.github.com/tbuktu/1576025/raw/447db955ef74b065b03b0b45abd443cea5d7b2c6/MutableBigInteger.java
> https://gist.github.com/tbuktu/1576025/raw/6863a38032835b48b73cbce5aa833680c881557f/BigDecimal.java
> https://gist.github.com/tbuktu/1576025/raw/11977be7d001e093baa915b4370f326e30218eec/BigIntegerTest.java

That is awesome: thank you so much! We are working towards getting this in before long as indicated in other messages.

> Semi-related: I think there is a bug in
> jdk/test/java/math/BigInteger/CompareToTests.java and
> jdk/test/java/math/BigDecimal/CompareToTests.java. It prints failures
> (with or without my patches) but the overall test doesn't fail.

Thanks for the pointer: will check it out.

Regards,

Brian