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

Alan Eliasen eliasen at mindspring.com
Mon Mar 4 23:24:16 UTC 2013

On 03/04/2013 03:37 PM, Dr Heinz M. Kabutz wrote:

Whilst we're at it, could we also add an option, perhaps via environment variable, to parallelize Karatsuba and other calculations?

Here's an article I wrote about the inefficiencies of BigInteger and working out large numbers: http://www.javaspecialists.eu/archive/Issue201.html

That's an interesting article, thanks.

When I first made the patches for faster multiplication, I was asked to generate small, simple patches so that they would be reviewed more rapidly. I didn't make any attempt to use multiple threads, although these recursive divide-and-conquer algorithms would seem to be good candidates for such algorithms

Brian, as you may also not know, I have further patches to drastically improve the toString behavior of BigInteger using Schoenhage-Strassen recursive decomposition. This makes toString orders of magnitude faster for large numbers and will likely improve the performance of some of the stuff you're doing in BigDecimal as well. I will polish those up and submit them when you've reviewed the multiplication and pow fixes.

-- Alan Eliasen eliasen at mindspring.com http://futureboy.us/

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